"Merciless" Ray Mercer is an American professional boxer. Born in Jacksonville on April 4, 1961 he is a former WBU heavyweight champion.

He won gold in the 1988 Olympics in Seoul as a heavyweight. His professional career starting in 1989, with a TKO of Jesse Hughes, Mercer made a name for himself with his win over Tommy Morrison in 1991 to retain the WBO heavyweight title that he had taken from the previously unbeaten Francesco Damiani in Atlantic City earlier that same year.

He then suffered defeats to Larry Holmes (1992), Jesse Ferguson (1993), Evander Holyfield (1995) and, in controversial circumstances, Lennox Lewis (1996) before taking time out of boxing in 1997 due to problems with hepatitis B. Resuming his boxing career in 1998, he strung together a number of early round knockouts over journeymen such as Leo Loiacono, Jeff Pegues, Don Steele and Bryan Scott before losing to WBO Heavyweight Champion Wladimir Klitchko in 2002.