The Coen brothers spring to mind (Fargo, Brother Where Art Thou). They credit Roderick Jaynes in all their movies as film editor, though they do it themselves. Apparently they’ve had Albert Finney pretend to be Roderick Jaynes.
Would the gag credits in Zucker-Abrams-Zucker films count? “Worst Boy: Adolf Hitler” often appears after the best boy, and “Foreez: A Jolly Good Fellow” shows up a lot, too.
Fargo doesn’t credit Prince; one of the crew made a goofy, Prince-like symbol and put in the credits for himself. I think there’s a smiley face in the middle of it.