Which famous duo began in a 1940 MGM short called "Puss Gets the Boot"?

Puss Gets the Boot is a 1940 American one-reel animated cartoon and is the first short in the Tom and Jerry cartoon series. It was directed by William Hanna and Joseph Barbera, and produced by Rudolf Ising and Fred Quimby. As was the practice of MGM shorts at the time, only Rudolf Ising is credited. It was released to theaters on February 10, 1940 by Metro-Goldwyn-Mayer.

Puss Gets the Boot marked the debut of Tom and Jerry. In 1939, Joseph Barbera and William Hanna teamed up together in animation. Their first idea together was a cartoon series about a cat and a mouse. They built the cartoon but just as they were making the cartoon series theme, after releasing the short, the boss of MGM's cartoon studio, Fred Quimby, asked them to pursue other themes, believing that cat-and-mouse cartoons were old and boring. However, after the success of the cartoon, the first nomination for an Academy Award and a letter for a very important distributor in Texas asking for "more of the wonderful and delightful cat and mouse cartoons", Fred Quimby changed his mind.