“Rich Uncle Milburn Pennybags” first appeared in 1936. It’s believed that the character is at least partially based on legendary capitalist & financier J.P. Morgan. He was officially rechristened “Mr. Monopoly” by Hasbro in 1999.
By the way, the sad fellow behind bars is “Jake the Jailbird” and “Officer Edgar Mallory” is the cop who patrols the “Go To Jail” square.