Derrick "Smoke" Gainer (born August 22, 1972) is an American former professional boxer who competed from 1990 to 2012.

Gainer is a colleague and friend of fellow Pensacola, Florida native Roy Jones Jr., and often fought on his under-cards.

[citation needed] In 2000, Gainer defeated Freddie Norwood to win the WBA featherweight title and after four defenses lost to Juan Manuel Márquez, who became super champion, via technical decision in 2003.

[2][3][4] Since his defeat to Marquez, Gainer lost in a challenge to WBA titleholder Chris John via unanimous decision.

[5] His last was a split decision win over Carlos Navarro on the undercard of the Roy Jones-Anthony Hanshaw bout at the Mississippi Coast Coliseum, in Biloxi, Mississippi.