Mr. Xerox was one of the early crackers on the Apple II and created some of the earliest animated crack screens.

He is credited with dozens of cracks for games going back to 1981. And is the author of a number of cracking tutorials including, MR. XEROX'S CRACKING TIPS II:CRACKING SPACE RAIDERS APRIL 1982 and MR. XEROX'S CRACKING TIPS III:CRACKING BUG ATTACK APRIL 1982.

There was a Mr. Xerox on the Amiga and PC who maybe the same person.