Between graduation and getting professional comedy gigs – as it's becoming something of a theme in this gallery – Billy Crystal was a substitute teacher on Long Island.
The world famous singer Sting has already worked as an English teacher as well as a music instructor. Before "Sting's" (whose real name is Gordon Sumner) music career took off, he also worked as a construction worker.
Ex U.S. president Barack Obama was teaching constitutional law at the University of Chicago Law School for twelve years, before he started his career as a politician.
Mad Men star Jon Hamm used to be an acting coach in Missouri. This is also where he was first discovered and started getting smaller roles before his career really took off...