Here's a great little video from the 1980s featuring a young Tim Burton on the Disney studio lot being harassed by by future Pixar movie director and Disney Executive John Lasseter. The look on Burton's face is hilarious, he has no idea what is going on, he's just got the dumbfounded look.
Burton started his career as an animator at Disney working on film projects such as The Fox and the Hound and TRON. He eventually started making his own short films, both animated and live-action. In 1984 he ended up making his Frankenweenie short which ended up getting him fired, because it was too dark and twisted for the studio. As you know years later he ended up turning it into a feature film for the same studio that fired him for it.
I've also included an animated short from the director that he made shortly after he graduated from Cal Arts. It's called Stalk of the Celery Monster.