John “The Quietman” Ruiz is a former American professional boxer. Ruiz is the first Latino heavyweight champion and a former two-time WBA heavyweight champion. After a professional career spanning over 18 years, Ruiz officially announced his retirement from the sport at a press conference on April 26, 2010. His final fight was a title shot against the then WBA heavyweight title holder David Haye, in which Ruiz was defeated by TKO in round 9.

Ruiz has defeated three world champions in Evander Holyfield, Hasim Rahman, and Tony Tucker, as well as top contenders such as Andrew Golota, Fres Oquendo, Jameel McCline, and Kirk Johnson.

He currently resides in Las Vegas, Nevada.