Pablo Mármol
Sidney became good friends with MGM animation directors William Hanna and Joseph Barbera. Hanna and Barbera's Jerry Mouse appeared alongside Gene Kelly in Sidney's film "Anchors Aweigh" (1945). After MGM closed its animation studio in 1958, Sidney helped Hanna and Barbera form a deal with , the television division of Columbia Pictures, to form the successful television animation studio Hanna-Barbera Productions, and was a shareholder in the company. Sidney later featured Hanna-Barbera's Fred Flintstone, Barney Rubble, Huckleberry Hound, and Yogi Bear in "Bye Bye Birdie" (1963).