Charles L. "Sonny" Liston (1930 – December 30, 1970), nicknamed "the Big Bear", was an American professional boxer who competed from 1953 to 1970. A dominant contender of his era, he became the undisputed world heavyweight champion in 1962 after knocking out Floyd Patterson in the first round, repeating the knockout the following year in defense of the title; in the latter fight he also became the inaugural WBC heavyweight champion. Often regarded as one of the greatest boxers of all time, Liston is known for his immense strength, formidable jab, long reach, toughness, and is widely regarded as the most intimidating man in boxing history.
Although Liston was widely regarded as unbeatable, he lost the title in 1964 to Muhammad Ali (then known as Cassius Clay), who entered as an 8:1 underdog. Liston retired in his corner due to an inflamed shoulder. Controversy followed with claims that Liston had been drinking heavily the night before the fight and had entered the bout with a lame shoulder. In his 1965 rematch with Ali, Liston suffered an unexpected first-round knockout that led to unresolved suspicions of a fix.