Della Duck, also known as Dumbella Duck and Thelma Duck, is Donald Duck's sister and the daughter of Hortense McDuck and Quackmore Duck. She is also the mother of Huey, Dewey, and Louie, Donald's triplet nephews.
Della has rarely appeared in any stories, so information about her is largely unknown. According to chapter 11 of the Eiser Award-winning comic book series The Life and Times of Scrooge McDuck, Della and Donald are twins. However, when the story's author, Don Rosa, was later told that Donald and Della being twins (instead of Della being older than Donald) would raise timeline issues, Rosa said that Donald and Della might be twins, but they don't necessarily have to be, leaving it up to the interpretation of the reader:
|“||Yes, I DO like the idea of Donald and Della being twins. But, as you say, if I simply OMIT that one comment, everything works out fine just as it is (...) Della and Donald still look like twins, and maybe they are... but I don't think anyone can trip me up on years if I don't nail it down needlessly. I think my Duck Family Tree will be in Walt Disney's Comics & Stories #600, but naturally birth years won't be listed, and it's not possible to tell if siblings are twins or not on that tree.||”|
— Don Rosa, Disney Comics Mailing List, July 1994
The relationship with her sons and Donald, and why she leaves them with her brother, is inconsistent. In the original comic strips in which Huey, Dewey, and Louie were introduced, Della was around to take care of the boys and did miss them when they were with Donald, and, despite always remaining an invisible character, would correspond with Donald via letter, telegram and over the phone; in fact, one instance showed that she was more than happy to have them back after Donald had grown tired of them. However, as of the 1942 cartoon The New Spirit, the nephews were listed as being adopted by Donald.
According to the Dutch Disney comic 80 is Prachtig, Della was one of the first female pilots, and eventually became an astronaut, so she left her infant children with her brother just before she left for a space trip. Coincidentally, Donald already mentioned having numerous pilots in his family in the 1942 theatrical short Donald Gets Drafted ("I come from a family of aviators! My father, my uncle, my cousin..."). This is also carried into the 2017 version of DuckTales, where it is shown that Donald raised the boys on his own after Della was lost in outer space.
Donald's sister was first mentioned in the cartoon short Donald's Nephews (1938), in which she sent her sons Huey, Dewey, and Louie to visit Donald. In the letter, she was referred to as Dumbella Duck.
In the newspaper comic strip of November 21, 1937, Donald, who has grown increasingly tired of his nephews, receives a telegram from Della in which she says that she wants Huey, Dewey, and Louie to come back home, which they do, much to Donald's pleasure. However, the trio returned to appear in the comic strip not long after their departure, in a May 1938 installment of the comic strip. Here, Huey, Dewey, and Louie's mother phones Donald, with only the following part of the phone conversation being given to the reader: "― and I have to go out of town for a while, and I knew you'd love to keep the little dears!". Donald begrudgingly accepts, and his nephews immediately speed into his house on their tricycles.
The nephews' mother made her first visual appearance in Mark Worden's illustrated version of Carl Barks' Duck family tree, by the name Thelma Duck, which had been given to her by Barks himself. However, in Don Rosa's Duck Family Tree, first published in 1993, she was given the first name Della again (presumably to keep the alliteration), except she appeared on the tree as Donald's sister and not as his cousin. Della later made a cameo as a child alongside her brother and her parents in Rosa's The Empire-Builder from Calisota, chapter 11 of The Life and Times of Scrooge McDuck.
Della reappeared in the comic titled 80 is Prachtig (written by Evert Geradts and drawn by Maximino Tortajada Aguilar), where she was given a new history and background as one of the first female pilots, who eventually became astronaut, leaving her children with her brother just before she left for a space trip, only to get lost in space after a faulty rocket launch. This comic was made in honor of Donald Duck's 80th anniversary in 2014 and was published in a special issue of the Dutch Donald Duck magazine.
A younger Della continued to appear in the Dutch Donald Duck comics (also scripted by Geradts) throughout 2017 in the "Donald's Eerste" (Donald's first) line of one-page gag comics showing young Donald's first experience with computers, traveling and a variety of other things.
Della makes her animated debut in the series. In this incarnation, Della was a pilot and traveling companion of Scrooge and Donald. She, like Scrooge, was brave, ingenious, and eager during adventures, although her impetuous and stubborn side led her group into trouble much of the time, much to Donald's dismay and worry. She also wasn't above making light-hearted jokes at her brother's expense. The mystery of Della's absence in the nephews' lives is a central story thread in the first season of the show, with the ending of the series premiere having Dewey discover a painting, showing that she was previously a companion of Scrooge and Donald in their adventures. Unlike most portrayals of the character, her hair color is now white as opposed to blonde. She also has a prosthetic leg in the present.
In "The Great Dime Chase!", Dewey goes to Webby Vanderquack for information about Della, mentioning that Donald had never said more than one word about her and their only memento of her is a photo of Della pushing Donald's face into a cake. Sadly, Webby has little to no information on Della, as though she had disappeared off the face of the earth. She mentions that Scrooge bought the post office the day after a mailman delivered a piece of junk mail addressed to Della. Thus, Dewey and Webby go to the archives at The Money Bin but Miss Quackfaster kept stalling them with so-called trials. Eventually, Dewey finds a book titled with his mother's name and the only entry is a reference number, which led him and Webby to a secret room, where they find a letter from Della to Scrooge, revealing she had stolen the Spear of Selene, which was mentioned in "Woo-oo!". Fearing the possibility that his mother betrayed Scrooge, Dewey tells Webby to hold off telling anyone until they know more.
In "The Spear of Selene!", when the family crashes on Ithaquack, Dewey and Webby investigate the Temple of Heroes for clues to Della's whereabouts, while debating whether she took the Spear of Selene for nefarious or altruistic purposes. Eventually, they meet the moon goddess, Selene, who tells Dewey that his mother was a true hero who loved her family. Unfortunately, Selene has no idea what the spear is, though she insists that Della would never have betrayed her family. Selene then gives Dewey the Sphere of Selene, which allows him to see images of his mother.
In "The Last Crash of the Sunchaser!", Dewey, Huey, Louie, and Webby continue searching for the truth about Della. Louie recovers a shredded document from Scrooge's archives, but one of the pieces gets lost while they are on the Sunchaser. When Dewey finds the piece, the plane suddenly crashes into a steep peak, forcing the group to mind their movements to balance the plane. After Dewey successfully retrieves the piece, ignoring Scrooge's requests to follow him to safety, he demands Scrooge tells him what the Spear of Selene is. Scrooge explains that it was a rocket ship he built because Della wanted to explore outer space, but Donald didn't agree with her plans because he thought the idea was too risky, and her triplets were about to hatch. Even so, Scrooge decided to build the rocket without anyone's (including Donald's) consent, and he took a picture of it, intending it to be a surprise for Della to celebrate her triplets' birth. Unbeknownst to Scrooge, Della had found out early and climbed into the rocket without him noticing. Scrooge contacted Della and tried to talk her through a cosmic storm that came out of nowhere. The ship got hit by a lightning bolt, causing the ship's transmission to cut out, leaving her stranded in space. The kids, heartbroken, resent Scrooge because of this, and they, alongside Webby, Bentina Beakley, and Duckworth, leave the manor. Scrooge retreats to a study where he mulls over Huey, Dewey, and Louie's accusations that he did not do enough to save Della, while images of his efforts show that he sent other ships to find her and lost most of his money searching for her before his financial advisors shut the efforts down.
It is revealed at the end of "The Shadow War!" that Della had survived the storm and crash-landed on the moon. Her television picks up a broadcast from Earth, depicting the Scrooge, Launchpad, Mrs. Beakley, Webby, Huey, Dewey, and Louie victorious over Magica De Spell. She gasps when she sees her sons.
In "Last Christmas!", Dewey meets with a younger incarnation of his mother who is trying to hunt Santa. It is revealed that the name "Dumbella" is actually an insulting nickname given to her by Donald. As they were chased by a wendigo, actually the cursed form of the Ghost of Christmas Past, Dewey gets Donald to apologize to Della for not spending the holidays with her. After captured the wendigo, Dewey hugs Della, but she easily sees through his lie about being a distant relative, guessing he's actually from the future, given that his appearance was the fourth weirdest thing to happen to them on Christmas and thus refuses to be told what happens to her in the future as doing so could fracture the space-time continuum. In the present, Della gets to work on her rocket in the hopes of returning to Earth and her family.
In "What Ever Happened to Della Duck?!", it is shown that Della Duck had survived on the moon for a decade, thanks to chewing on Gyro Gearloose's Oxy-Chew gum. Unfortunately, she had to sacrifice her left leg to escape from under some wreckage, replacing it with an artificial one. Della spent years rebuilding the Spear of Selene while battling a metal-eating creature called the Moon Mite. She also combed the Moon for gold, the rocket's source of fuel, coming up short until discovering gold fillings in her teeth. While fighting the Moon Mite for the gold, Della is found by two Lunarian cops, Lunaris and Penumbra, who were also battling the creature. After an underground scuffle, Della and the Lunarians learned the Moon Mite had taken the Spear of Selene to feed its offspring, and Della, empathetic to the Moon Mite's plight, gave up her gold. She was later taken to Tranquility, the Lunarians hidden civilization. Once she realized the city's main resource was gold, Della became hopeful again in fixing her ship and finally returning to Earth.
In "The Golden Spear!", Della tries to fix her ship with the gold that she found. General Lunaris has Della and Lieutenant Penumbra to room together. Penumbra still thinks that Della is bad. Della tells her stories to her new "friends" Gibbous, Zenith, and the other aliens. They are all amazed and asks if they could go to earth with Della. Della agrees she'll take them but however, Penumbra starts her ship and leaves them behind. She soon returns home to McDuck Manor.
In "Nothing Can Stop Della Duck!", Della finally returns to McDuck Manor, tearfully reuniting with her Uncle Scrooge, who is deeply impressed with her survival on the Moon. Della also finally meets her sons Huey, Dewey, and Louie, though it is briefly irritated to discover Donald had not named them Jet, Turbo, and Rebel as detailed in the instructions she had left behind. Though Della is welcomed back into the family, she quickly discovers herself ill-prepared to be the mother Huey, Dewey and Louie had lacked, unwillingly traumatizing them through inedible food, terrifying tales, and stunts that nearly result in injury. Della's trouble over her inability to connect with her sons only intensifies after learning Scrooge hired Launchpad to become his new pilot, and on her way to complain to him, overhears him declare she is not a proper mother, though she leaves before hearing Scrooge continue to say she needs more time to adjust. Della in her frustration ends up inadvertently awakening the Gilded Man within Scrooge's Garage. The family soon arrives to help Della defeat the monstrous machine, leading them to all reconcile, with Della promising to work harder to become a proper mother.
In "Raiders of the Doomsday Vault!", Della and Dewey search for the money tree seed at the Von Drake Doomsday vault, causing the two to bond over their love for adventure. As the traps and dangers become more perilous, Dewey becomes more and more determined to prove himself to his mother, to the point that even Della grows concerned they are in over their heads. After being saved by Scrooge, Dewey and Della open up to each other, the latter declaring Dewey has no need to prove himself to her, as she loves him no matter what.
In "Happy Birthday, Doofus Drake!", Della and Huey play a VRMMORPG known as Legends of Legendquest: Dereznaroth. While Della is busy having the time of her life, Huey tends to a garden inside his little farm. Concerned, Della convinces Huey to play outside his competence zone to have more fun. Instead, Huey lets loose a little more than she expected and has to take Huey away from the game.
In "The Golden Armory of Cornelius Coot!", Della ends up aiding Launchpad into piloting an airplane for real. She grows incredibly frustrated by Launchpad's inept flying skills, though she is impressed by what he's done despite it. However, after talking to Webby and convincing her that she needn't try to one-up her, Della realizes she was doing that towards Launchpad and goes to apologize to him.
In "Timephoon!", Louie's get-rich-quick schemes mess around with time-space, saddling Della with aiding Mrs. Beakly in trying to take care of the house, even going off to fight a ninja with her and dealing with Bubba the Cave Duck. Despite Louie fixing the mess he caused, Della is furious with Louie for his actions. In anger, Louie throws back Della stealing the Spear of Selene as proof that the apple doesn't fall far from the tree. Despite this and everyone agreeing with him, Della grounds Louie and forces him to shut down his company.
In "GlomTales!", her punishment towards Louie continues, having thought up of various ways to keep Louie in his room while she and the rest of the family head off to Big Rock Candy Mountain for the easiest adventure ever. Her videos to Louie try to convince him to stop his schemes as all they do is hurt others. Della is present when Flintheart Glomgold and a gathering of foes the Duck-McDuck clan has faced arrived to attack them, Della fighting off the Beagle Boys. When Louie steps up and reveals he's behind helping Glomgold win his bet against Scrooge, the group is disappointed in Louie. However, Della realizes that Louie's scheming can help out people, and promises to help him see things that he can't. However, she's worried when Louie doesn't immediately return everything to Scrooge.
In "The Richest Duck in the World!", Della wonders why the Moonlanders Haven't come to earth yet. She tries to contact Penumbra but doesn't get a response. Della goes on Dewey Dew-Night! to transmit her message to Penumbra. Della discusses her relationship with Penumbra on Dewey Do-Night!, only for Dewey to note that evidence is in favor of Penumbra hating her rather than being her friend. Afterward, Penumbra then warns Della and her family about the alien invasion. This is due to Louie's attempts to stop the Bombie.
In "Moonvasion!", Della warns Scrooge just as Lunaris' invasion began. While Scrooge mounted a counterattack, Della takes her kids and Webby around the world, ostensibly to gather allies before Louie deduced she was only seeking refuge for them. Della admitted she was driven by fear of losing her kids, unaware that she had played right into Lunaris' hands, as she was the only one who could've thwarted the invasion. When the Moonlanders ultimately shot them down, causing the Sunchaser to crash on an island, she reunites with her brother Donald, who came from the Moon, where he explains that he met Penumbra on the Moon. They soon reunite with their cousins Gladstone Gander and Fethry Duck atop the latter's giant shrimp and return to Duckburg to assist Scrooge. The McDuck family goes into space to defeat General Lunaris in order to end the war between Earthlings and Moonlanders, though Della and Donald fought over the controls. Ultimately, while targeting Lunaris' ship, they were pinned between his cannons until Penumbra appeared and rammed the original Spear of Selene into Lunaris' engine, ending the invasion.
In "Challenge of the Senior Junior Woodchucks!", Della dons her old Junior Woodchuck uniform as she attends Huey's graduation ceremony. While Huey and Violet compete for the honor of senior Woodchuck, Della follows Scrooge on an adventure to find Isabella Finch's treasure. She is forced to contend with a mosquito that is bothering Donald; unbeknownst to her, though, the mosquito is a drone piloted by F.O.W.L.
In "Quack Pack!", Della follows Finch's journal to the treasure of Collie Baba. As a result of Donald accidentally summoning Gene the Genie while wishing for the family to have normal family problems, Della is sucked into a sitcom reality where she is portrayed as a fun mom who explains her actions with "Back on the moon..." In the sitcom, as Della, Scrooge, and Louie fix the study, Huey eventually forces the three to look at the fourth wall, making them realize they are trapped in a sitcom. The family finds Gene, who explains that Donald has to wish them out of reality. As the studio audience attacks them, Donald is eventually able to retrieve the lamp and make his wish, ending the sitcom.
In "The Lost Harp of Mervana!", it is revealed that Della has a fear of fish.
Although Della never appeared in the classic cartoons, she was mentioned on rare occasions throughout Disney's published comics.
A comic adaptation of the short Donald's Nephews was written into the Donald Duck newspaper comic strip of 1937, in which it was told that the nephew's father was in the hospital after a giant firecracker had exploded under his chair. In this comic, Della was still said to be Donald's cousin, rather than his sister.
Della appears in the comic adaptation of the 2017 series, specifically in stories that were set before the series. These stories feature the adventures she attended with Donald and Scrooge.
- "Della" was also the first name of Al Taliaferro's aunt.
- In an early French translation of the comic adaptation of Donald's Nephews, Huey, Dewey, and Louie were sent to Donald by Clarabelle Cow instead of his sister.
- Della made a very obscure cameo appearance in Don Rosa's The Sign of the Triple Distelfink. During a flashback to Donald and Gladstone's childhood, she can be seen in the background at young Gladstone's birthday party.
- Della's introduction was the first time a Sensational Six member was explicitly said to have a sibling (Morty and Ferdie's mother was already introduced in 1932, but she was said to be Mickey's sister years after her first appearance, while Oswald the Lucky Rabbit was introduced in 1927, but he was confirmed to be Mickey's older brother 75 years later in Epic Mickey 2: The Power of Two).
- In The Duck Who Never Was by Don Rosa, it's shown that if Donald wasn't born, Della would have left her children with her cousin Gladstone.
- In the 2017 reboot of DuckTales, Della is shown wearing a pilot's outfit, perhaps as a parallel to her brother's sailor attire and/or a nod to her occupation in Donald's 80th-anniversary comic.
- She was a Junior Woodchuck in the 2017 series.
- Della is referenced in the PKNA comic series when Donald is asked if he has a sister and answers positively (issue #24 Twilight).