Disney Studios practically owns the rights to the Best Animated Short Oscar - the studio has 49 nominations and 18 wins. Which studio, with 23 nominations and 9 wins is second to Disney? This studio's greatest success was with the work of producer Pat Quimby who won Oscars for works such as The Yankee Doodle Mouse, The Cat Concerto, and The Two Mouseketeers.
MGM (Metro Goldwyn Mayer - they were Tom & Jerry cartoons) (edited at 8:05 pm, April 2, 2021 (PDT))
Original Answer: MGM (Metro Goldwyn Mayer - there were Tom & Jerry cartoons)