In 1940 Mickey Rooney (né Joe Yule, Jr.: b. 1920 - 2014) had replaced Shirley Temple as the number one box-office draw. Having worked steadily before the cameras from the age of six onward, Rooney had been jockeying for first place since he began playing the title roll in the Andy Hardy films just two and a half years earlier.
"Long before he ever saw Hollywood young Rooney was well on the way to acquiring the poise and audience sense that makes him the actor he is today. That he came up the hard way may account for the fact that the Mick today beats oldsters like Gable, Power, and Taylor."
You can read about Judy Garlin here.