Thunderbolt is a German Shepherd with brown fur and tan-colored paws.
He wears a red leather collar with a license of a yellow earnest star.
Thunderbolt is the Dalmatian pups' favorite TV show hero. In the show, he is shown to be chasing Dirty Dawson, with the horse thief shooting at him. Dawson then travels on foot as Thunderbolt searches. In some scenes, it shows Thunderbolt making a leap across a canyon before it seems like Dawson has shot Thunderbolt. However, Thunderbolt is only pretending and as Dawson laughs about this, Thunderbolt then attacks. The two fall into a river, having the show end in a cliffhanger as they are about to fall down a waterfall.
In the show, Thunderbolt is joined by his offbeat sidekick Lil' Lightning fight to defeat Dirty Dawson.
In an episode, Dirty Dawson kidnaps a helpless boy named Tommy. It is up to Thunderbolt and Lil' Lightning to defeat him before any harm befalls Tommy. As Dawson ties Tommy to a moving train, Thunderbolt perches on a cliff. He jumps to the train, confronting Dawson. Whilst Thunderbolt fights Dawson, Lil' Lightning unties Tommy. Dawson causes Thunderbolt to stumble between the train carts and as he is about to strike Thunderbolt, another train heads by the train carts they are on, allowing Thunderbolt to get around Dawson. Thunderbolt then tangles Dawson in his own whip, tripping him up and making him fall into a boxcar with a mad bull. Tommy is then rescued and Thunderbolt saves the day.
While watching The Thunderbolt Adventure Hour, Patch, longing to feel one-of-a-kind like his hero Thunderbolt, hears about a chance to appear on the show while it is filming in London. However, when Roger, Anita, and the 101 Dalmatians plan to move to the Dalmatian Plantation, the family move will interfere with Patch's opportunity – until he is accidentally left behind in the commotion. Patch heads for the audition to meet his hero. Meanwhile, Lil' Lightning tells Thunderbolt the producers want to replace him with a younger dog.
In order to save his job, Thunderbolt decides to go into the real world and perform an act of true heroism to prove himself. A veritable reference book to Thunderbolt's many adventures, Patch provides the perfect guide for Thunderbolt in his attempts at real-life heroics.
At first, Thunderbolt is arrogant and selfish, seeming only to care about his job and his popularity. He is very popular with other dogs, all the ladies love him, and Patch is his biggest fan, knowing all of his episodes by heart. As the film goes on, Thunderbolt becomes more kind and helpful, and he and Patch start to become friends. Furthermore, he is willing to assist those in need and is not afraid to admit he is just an actor and all his rescue missions on his show are fake. He is also cunning and highly skilled with his acting as seen when he tricks Cruella De Vil, Jasper, Horace, and Lil' Lightning into thinking he is having a heart attack.
A post-credits scene shows Thunderbolt with his new sidekick Patch in his TV show The Thunderbolt Adventure Hour.
In 101 Dalmatians: The Series, Thunderbolt is the star of a show titled Thunderbolt P. I., where he works with a James Bond-like partner named Rex Hunter. There are also a number of villains in said show, such as Bone Daddy, Doctor Wonko, the Masked Marauders, and even his evil twin.
Thunderbolt also appears in "Kanine Krunchies" advertisements (including the one from the original film) and even stars in his own film.
Thunderbolt made a physical appearance in "Watch for Falling Idols," where he and his creators arrive on the Dearly Farm to film their next episode. Lucky is thrilled to meet his idol and tells Thunderbolt he is his biggest fan and that they once met at the Gruteley County Fair, where Thunderbolt supposedly autographed a picture. Lucky also claims to have seen all of Thunderbolt's movies. Before the episode is filmed, Thunderbolt is seen relaxing in a hot tub inside his trailer, where he is idolized by Lucky, who even waits on him. However, when Lucky later finds out that Thunderbolt doesn't do his own stunts (after Thunderbolt panics from being lifted off the ground, due to his fear of heights), he shuns Thunderbolt and loses faith in him. Later on, Lucky tries to prove he's brave by climbing up the TV windmill, but ends up putting himself in danger instead. Fortunately, Thunderbolt notices Lucky in trouble and, pushing his fears aside, manages to rescue his young fan. Lucky thanks Thunderbolt who tells him that a hero isn't one who fears nothing, but is one who is willing to overcome his fears. Lucky agrees with Thunderbolt and they reconcile.
The One Hundred and One Dalmatians Diamond Edition Blu-ray features a Thunderbolt short based on early drafts of the scene, which follows the events directly from where they are seen in the animated 101 Dalmatians.
The short shows that Thunderbolt and Dirty Dawson are able to catch branches sticking from the side of the waterfall. Dawson is able to reach a ledge and as Thunderbolt's branch is about to snap, his human, the sheriff, is able to use his lasso to save him. The two pursue Dawson, but the thief uses explosives to cause an avalanche, blocking their path and allowing him to take some sacks of money from a wagon, which may be why Thunderbolt is chasing him. The sheriff thinks Dawson has escaped, but Thunderbolt climbs across the rock pile to continue the chase. In the end, thanks to Thunderbolt, Dawson is nabbed and brought to justice.
- Thunderbolt is similar to Flash the Wonder Dog from Chip 'n Dale Rescue Rangers as both are famous heroic dogs who do not do their own stunts, both are the stars of their very own shows, and both are idolized by another animal character (Patch / Lucky for Thunderbolt; Dale for Flash).
- In the 101 Dalmatians: The Series episode "Frisky Business," when Thunderbolt introduces himself in the "Kanine Krunchies" advertisement, he barks it in a similar style to how James Bond introduces himself.