Born in Fresno, California, Frank Thomas attended Stanford University, where he worked on campus humor magazine The Stanford Chaparral with Ollie Johnston. After graduating from Stanford, he attended Chouinard Art Institute, then joined The Walt Disney Company on September 24, 1934, as employee number 224. There he animated dozens of feature films and shorts, and also was a member of the Dixieland band Firehouse Five Plus Two, playing the piano.
His work in animated cartoon shorts included Brave Little Tailor, in which he animated scenes of Mickey Mouse and the king; Mickey and the bear in The Pointer, and German dialogue scenes in the World War II propaganda short Education for Death (shortly before Thomas enlisted in the Air Force).
In feature films, among the characters and scenes, Thomas animated were the dwarfs crying over Snow White's "dead" body; Pinocchio singing and dancing at the marionette theatre, Bambi and Thumper having fun on the ice; Lady and the Tramp eating spaghetti on their date in Lady and the Tramp; Flora, Fauna, and Merryweather in Sleeping Beauty; Merlin and Arthur as squirrels, and the "wizard's duel" between Merlin and Madam Mim in The Sword in the Stone (in which he was paired with animator Milt Kahl to great effect); King Louie in The Jungle Book (the song number "I Wan'na Be Like You" featuring King Louie and Baloo the Bear dancing, which re-teamed him with Kahl); the dancing penguins in Mary Poppins; and Winnie the Pooh and Piglet in the Winnie the Pooh featurettes. He was also a directing animator for several memorable villains, including the evil stepmother Lady Tremaine in Cinderella, Queen of Hearts in Alice in Wonderland, Captain Hook in Peter Pan, and Aunt Sarah in Lady and the Tramp and other characters in The Fox and the Hound.
Thomas co-authored with fellow Disney legend Ollie Johnston on the comprehensive book The Illusion of Life, first published by Abbeville Press in 1981. Regarded as the definitive resource book on traditional hand-drawn character animation (particularly in the Disney style), the book has been republished numerous times and is widely considered "the bible" among character animators. The book summarised the Disney approach to animation through the so-called 12 basic principles of animation.
In a likely reference to the book, the Adventures of the Gummi Bears episode "Light Makes Right" contains a scene featuring the children's book Tall Tales of The Gummi Bear, which contains a page with the words "Two of Gummi's famous Nine Old Bears, Frank and Ollie", honoring both animators with a blink-and-you-miss-it inside joke.
Thomas and Johnston were also profiled in the 1995 documentary Frank and Ollie, which screened at the 20th Toronto International Film Festival, directed by Thomas's son Theodore Thomas. The film profiled their careers, private lives, and the personal friendship between the two men.
Thomas' last appearance in an animated film before his death was in The Incredibles (directed by Brad Bird), although he voiced a character, rather than animating one. Frank and his friend and colleague Ollie Johnston voiced and were caricatured as two old men saying "That's old school..." "Yeah, no school like the old school." The pair had previously been heard, and caricatured, as the two train engineers in Bird's The Iron Giant. Three days after his 92nd birthday, Frank Thomas died in Flintridge, California.
The 2001 biography Walt Disney's Nine Old Men & The Art of Animation by John Canemaker (ISBN 0-7868-6496-6) chronicles Thomas' life.
On the Animation Podcast, Disney director John Musker discussed Frank Thomas, and mentioned that at one time, fellow animation great Chuck Jones had christened Thomas the "Laurence Olivier of animators".
Characters animated by Thomas
- Snow White and the Seven Dwarfs: Dwarfs crying over Snow White's death body
- Pinocchio: Pinocchio
- Bambi: Bambi
- The Adventures of Ichabod and Mr. Toad: J. Thaddeus Toad, Cyril Proudbottom, Water Rat, Mole, Brom Bones
- Cinderella: Lady Tremaine
- Alice in Wonderland: Queen of Hearts
- Peter Pan: Captain Hook
- Lady and the Tramp: Aunt Sarah, Lady and the Tramp eating spaghetti on their date
- Sleeping Beauty: Flora, Fauna, and Merryweather
- The Sword in the Stone: Girl Squirrel, Merlin and Madam Mim
- Mary Poppins: Penguins Waiters
- The Jungle Book: King Louie, Baloo, Mowgli and Kaa
- The Many Adventures of Winnie the Pooh: Winnie the Pooh, Piglet
- The Rescuers: Bernard, Miss Bianca, Nero and Brutus
- The Fox and the Hound: Copper
Books (all with Johnston)
- The Illusion of Life: Disney Animation
- Too Funny For Words: Disney's Greatest Sight Gags
- The Disney Villain (ISBN 1-56282-792-8)
- Bambi: The Story and the Film, accompanied by a flip book