Grim Natwick was instrumental in bringing Snow White to life. Grim had eight years of art school training, worked for Fleisher, Disney, and Iwerks among others. He was given the lead on Snow White and animated 120 scenes working with some of the best assistants (like Marc Davis).
He joined Disney after working at Feischer studio:
it was in 1930 I created Betty Boop and instantly Walt Disney offered me a job and every other studio in Hollywood. Every one of them had been trying to create a girl character and couldn’t do it. The artists....drawing a girl is different from Mickey Mouse or Minnie Mouse or Bugs Bunny or things that are funny little characters. But Snow White had to be almost a real character and the reason was very simple: I had about eight years of art school experience and most of these kids had maybe a year or two at one of the smaller schools.
There are three Snow Whites that appear in the final film: done by Luske, Campbel and Natwick. Luske: the scene with the bluebird in the forest, Campbell: the scene at the wishing well, and. Natwick: the sequences where she investigates the Dwarf's cottage, the house cleaning scenes, the dancing scenes and the "Someday My Prince Will Come" sequence. Natwick is credited with drawing the most lifelike version.
Grim left the Disney studio when he was passed up for a promised bonus. Story goes that the rivalry was strong between Luske and Natwick and that Luske got the bonus check for Grim's work. To read more about his work see ASIFA Hollywood Animation Archive.
David Johnson interviewed Grim in 1988. The interview is a little convoluted as Grim was in his nineties. To see the full interview see the Inside Animation Page.