Screen credit is valuable only when it's given you. If you're in a position to give yourself credit, you don't need it.

Quoted by Norman J. Zierold in The Moguls (New York: Coward-McCann, 1969). Also quoted as "Credit you give yourself is not worth having." Thalberg never took an onscreen credit in films he produced; MGM gave him a screen credit for The Good Earth (1937), released after his death.