The founder of, president of, and programming genius behind Epic Games. He started Epic with shareware games such as ZZT and Jill of the Jungle, took a producing role for a few years, and then proceeded to create the Unreal engine.
He has been programming since he was 13 years old. Epic Games operated out of the basement of his parents house from when it was founded in 1991 until mid-1992.
The games he has worked on (not including Unreal-engine based games he didn't directly work on) include the following:
Also the name of an independent music industry consultant, the founder of Tim Sweeney & Associates and the author of Tim Sweeney's Guide to Releasing Independent Records.