Mark Keil (born June 3, 1967) is a former professional tennis player from the United States who won five ATP Tour doubles tournaments and was runner up at eight more.

Prior to college, Keil was raised in Albuquerque, NM and in 1985 he was the New Mexico 4A high school state singles champion.

One of Keil's major career wins came in the second round of the 1991 Queen's Club Championships in London when he defeated Pete Sampras, then ranked 8th in the world, in straight sets.

He has doubles wins over Stefan Edberg, Boris Becker, Todd Martin, Tommy Haas, Andre Agassi, Gustavo Kuerten and Mark Philippoussis.

[2] His father, Klaus Keil, was an emeritus professor and a research scientist at the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii at Manoa.