I was thinking about the animators who first influenced me and helped my budding animation career at age 14. Grim Natwick comes to mind. Not only did he create Betty Boop and animate on Snow White, he was also picking up freelance at Duck Soup Productions from Duane Crowther in 1974. They were going over my first ever animation attempts, a recreation of an MGM Droopy scene which was way too tight. Duane showed me how to loosen up my stiff animation (done on a stereo record player cover as a lightbox).
Back at UPA, Grim was Duane's assistant. Here is a classic UPA short with some Grim Natwick animation in it from 1951...Rooty Toot Toot.
And here is Duane Crowther's rare student film Blum Blum from 1949. Duane went on to animate on The Beatles "Yellow Submarine".