Ollie Johnston, the last of the "Nine Old Men" of classic Disney Animators, passed away on Wednesday. Ollie started working with Disney doing "in-between" work on their animated shorts in 1935, and progressed along with the other eight into their now classic feature films. You can either check out his credit list at imdb.com, or you can just walk over to your shelf and look at every single Disney feature-length animated film you have that was produced before "The Little Mermaid". He worked on all of them.
You can see him below animated in Pixar's "The Incredibles" he is one of the two old men depicted after the robot fight scene in the city. He says "..now that's old school..." the other gentleman is another of the "Nine Old Men" Frank Thomas--who died in 2004 just prior to the official release.
They also appeared in and provided the voices for the train engineers in The Iron Giant.