Ub Iwerks was Walt's strong right arm in the 1920s. He was a designer and work-horse animator on the early Disney shorts, considered so valuable that he was a 20% owner of the studio.
But the 20% ownership ended when Iwerks departed Walt Disney Productions after a falling out with the majority owner. Bankrolled by movie mogul Pat Powers, Iwerks developed the frog character above, but within a few years flamed out as an animation kingpin and returned to Disney's.
The drawing above is from the Mega Collector's massive collection, file # 34-438. Mr. Mega believes it to be an Ub drawing. It was originally owned by Ub's son Dave.