MGM cartoon studio

The Metro-Goldwyn-Mayer cartoon studio was the in-house division of Metro-Goldwyn-Mayer (MGM) film studio in Hollywood, responsible for producing animated cartoons to accompany MGM feature films in Leow's Theatres. Active from 1937 until 1957, the cartoon studio created some popular cartoon characters, including Tom and Jerry and Droopy. 
Hanna-Barbera: Tom and Jerry (1939-1957)
Friz Freleng, briefly assigned to work under Harman, had returned to Schlesinger after his MGM contract was expired in April 1939, and storyman Joseph Barbera was united with director William Hanna to co-direct animated shorts for Rudolf Ising's unit. The partnership between Hanna and Barbera would last for more than six decades, until Hanna's death in 2001. The duo's first cartoon together was Puss Gets the Boot in 1940, featuring an unnamed mouse's attempts to outwit a housecat named Jasper. Though released without fanfare, the short was financially and critically successful, earning an Academy Award nomination for Best Short Subject (Cartoons) of 1940. On the strength of the Oscar nomination and public demand, Hanna and Barbera were assigned to direct more cat-and-mouse cartoons, soon christening the characters, Tom and Jerry. 
Puss Gets the Boot did not win the 1940 Academy Award for Best Animated Short, but another MGM cartoon, Rudolf Ising's The Milky Way did, making MGM the first studio to wrestle the Cartoon Academy Award away from Walt Disney. 
Tom and Jerry quickly became MGM's most valuable animated property. The shorts were successful at the box office, many licensed products (comic books, toys, etc.) were released to the market. 
The series would earn twelve more Academy Award for Short Subjects (Cartoons) nominations, with seven of the Tom and Jerry shorts going on to win the Academy Award: The Yankee Doodle Mouse (1943), Mouse Trouble (1944), Quiet Please! (1945), The Cat Concerto (1946), The Little Orphan (1948), The Two Mouseketeers (1951), and Johann Mouse (1952). Tom and Jerry was eventually tied with Disney's Silly Symphonies as the most-awarded theatrical cartoon series. Hanna and Barbera also produced/directed for the MGM cartoon studio half a dozen one-short theatrical cartoons besides the Tom and Jerry series, including Gallopin' Gals (1940), Officer Pooch (1941), War Dogs (1943), and Good Will to Men (1955). Fred Quimby was retired in 1955, with Hanna and Barbera replacing him in charge of the remaining MGM shorts (including the last seven Tex Avery's Droopy episodes) until 1957, when the studio shut down the H-B unit, ending all the animation productions.