McKimson's career extends back to the silent era when he began working as an animator trainee for the Walt Disney studio in 1928. He soon left Disney to join his older brother Tom at the Romer Grey cartoon studio. After that venture failed, McKimson was hired by Hugh Harman and Rudolf Ising to work as an animator at their new studio in 1930. He stayed aboard as they began making cartoons for distribution by Warner Bros. under producer Leon Schlesinger.Over the course of the decade, McKimson animated cartoon shorts under the direction of Friz Freleng, Frank Tashlin, Chuck Jones and Tex Avery before beginning a glorious five-year stint as Bob Clampett's head animator in 1941. He worked on some of Clampett's most celebrated works including "The Hep Cat," "Horton Hatches the Egg" (both 1942), "Tortoise Wins By a Hare" and "A Corny Concerto" (both 1943) and "The Old Grey Hare" (1944). McKimson's work was prized for how he gave figures weight while keeping them supple. This quality was especially useful for Clampett's work where character motion was particularly exaggerated and distorted.As the studio's principal model sheet maker [a series of drawings of a particular character in various poses and attitudes], McKimson determined the look and physical attitudes of some of the studio's most important characters. In 1943, under the guidance of the legendary animation director Tex Avery, McKimson drew the original model sheet on Bugs Bunny. That same year, he also drew the famous pose of a smiling Bugs Bunny leaning against a tree with a partially eaten carrot in his hand that subsequently became the standard publicity image for the beloved character. McKimson also claimed to have personally drawn over 150 Bugs Bunny insignia for branches of the Armed Services during WWII as the Warner Bros. characters began to decisively displace Disney's Mickey Mouse and company as America's favorite cartoon shorts.McKimson graduated to director when Clampett left the studio in 1946. He introduced his most important character, the garrulous barnyard rooster Foghorn Leghorn, in his fourth cartoon as a director, the Oscar-nominated "Walky Talky Hawky" (1946). This was the studio's first major "star" to be closely based on a pre-existing character--in this case, actor Kenny Delmar's characterization of Southern Senator Claghorn on the popular Fred Allen radio show. (McKimson traces Leghorn's evolution back even further to a sheriff character on an earlier radio show "Blue Monday Jamboree"). The character enjoyed a 17-year run in a series of pleasurable, if fairly formulaic, barnyard misadventures involving a nameless canine nemesis and a confused diminutive chicken hawk.McKimson supervised several other well-remembered series. He created a doubting son for Sylvester the Cat as well as a kangaroo, Hippity Hopper, who was invariably mistaken for a giant mouse in numerous father-son outings. McKimson also helmed a number of (now badly dated) TV parodies in the 50s. The best entries include "The Honeymousers" (1956), a parody of the classic Jackie Gleason sitcom, which generated two sequel cartoons, and "The Mouse that Jack Built" (1959), a parody of "The Jack Benny Show" featuring the actual voices of Benny, Mary Livingstone, Eddie 'Rochester' Anderson and Don Wilson.After the near demise of the Warner animation department, McKimson shifted to United Productions of America (UPA) where he worked on the primetime animated TV series "The Famous Adventures of Mr. Magoo" (NBC, 1964-65). McKimson joined DePatie-Freleng Enterprises as a freelancer and worked on their commercials, TV series and theatrical shorts. He briefly returned to the reopened but drastically diminished Warner Brothers' animation studio as the sole animator in late 1968. McKimson supervised the studio's last handful of theatrical shorts--made for less than half the previous budgets--featuring new but utterly forgettable characters. He finished out his career as a freelance animator/animation director.Ironically, one McKimson creation, the omnivorous Tasmanian Devil, achieved his greatest fame and popularity after his creator's death. Introduced in 1954 in "Devil May Hare," the whirling eating machine was deemed distasteful by executive producer Edward Selzer and ordered retired. However, studio head Jack Warner was a fan and demanded additional cartoons. "Taz" only grew in popularity over the years and had attained cult status by 1991 when "Taz-Mania" joined the afternoon lineup on Fox TV.