Gene Hazeltons career stretched from Fantasia to Flintstones. By his teenage years, he was a good enough cartoonist to get a job assisting Jimmy Hatlo on the popular newspaper panel, They'll Do It Every Time. In 1939, he took a low-level job at Disney and set some sort of record for working his way up to gag man and animator. He animated the goat kids and cherabims in Fantasia and a number of sequences in Pinocchio.
When a strike was called at Disney in 1941, Gene moved on to other studios, including Warner Brothers where he did the main designs for the legendary short cartoon, Coal Black and De Sebben Dwarfs, directed by Bob Clampett. He also began doing a lot of magazine gag cartoons and commercial art assignments. Here's a link to a piece by his friend, Scott Shaw!, reporting on the one comic book Gene drew.
Gene spent many years working with Bill Hanna and Joe Barbera at MGM on their Tom & Jerry cartoons and with Tex Avery on his highly-acclaimed shorts. When Gene Kelly wanted an animated sequence for his feature, Invitation to the Dance, Hazelton designed the "Sindbad the Sailor" sequence. There were also commercials and commercial jobs: The animated titles for the I Love Lucy TV show were also designed by Gene Hazelton — one of many such projects he handled for the studio.