Complex sentence: Charles L. "Sonny" Liston (unknown--December 30,1970) was an American professional boxer known for his toughness, punching power and intimidating appearance, who became World Heavyweight Champion in 1962 by knocking out Floyd Patterson in the first round.
Split into simpler sentences: Charles L. "Sonny" Liston (unknown--December 30,1970) was an American professional boxer known for his toughness, punching power and intimidating appearance. He became World Heavyweight Champion in 1962 by knocking out Floyd Patterson in the first round.