Muhammad Ali celebrates after knocking out Cleveland Williams in the second round of the World Heavyweight Title fight at the Astrodome in Houston, Texas on November 14, 1966. Many experts and boxers, including Mike Tyson, regard Ali's performance in this fight to be the finest of his boxing career.

United States President John F. Kennedy is photographed applauding from the stands during a December 1962 Army vs Navy college football game at Philadelphia Municipal Stadium.  A Navy lieutenant in World War II and an avid football fan, Kennedy stayed for the entire game and was delighted by Navy's 34-14 victory.

Joe Namath of the New York Jets is shown in uniform during a photoshoot at Life Studios in New York City on July 23, 1966. The shoot of the famous quarterback would go on to be featured on Sports Illustrated's October 1966 cover.

A battered Sylvester Stallone is photographed on set as Rocky Balboa during the filming of the boxing movie Rocky II in Los Angeles in November of 1978. The Rocky series follows the underdog boxer who fights numerous brutal opponents and wins the world heavyweight championship twice. 

Muhammad Ali poses for a photo at his training camp cabin in Deer Lake, Pennsylvania on January 9, 1974. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad Ali emerges from the darkness ready to fight during a photoshoot in Miami on April 2, 1965. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Sonny Liston throws a right hook punch toward Muhammad Ali during the first-round of the World Heavyweight Title fight at St. Dominic’s Arena in Lewiston, Maine on May 25, 1965. The photograph captures one of the most anticipated, watched, and controversial fights in the sport's history, which Sports Illustrated dubbed the fourth greatest sports moment of the twentieth century.

Muhammad Ali is photographed conferring with trainer Angelo Dundee in his corner during the World Heavyweight Title fight versus George Chuvalo at Maple Leaf Gardens in Toronto on March 29, 1966. Ali went on to win both fights against Dundee through unanimous decisions on points. 

Muhammad Ali is photographed walking back to his corner during the World Heavyweight Title fight against Floyd Patterson at the Las Vegas Convention Center in Nevada on November 22, 1965. Ali would go on to win the match as well as a later 1972 fight against Patterson through technical knockouts.

Pelé is photographed getting carried off the field by fans after winning the FIFA World Cup Final against Italy at the Estadio Azteca in Mexico City on June 21, 1970. The Brazillian footballer was instrumental in securing his team's way to the final, having scored 14 of Brazil's 19 goals in the tournament.

Willie Davis of the Los Angeles Dodgers is photographed sliding into second base during a game versus the Philadelphia Phillies at Dodger Stadium on April 25, 1965. At the end of his career, the center-fielder ranked seventh in major league history in putouts and total chances in the outfield, and third in games in center field.

Jockey Ron Turcotte is photographed riding Secretariat to victory and winning the Kentucky Derby at Churchill Downs in Louisville, Kentucky on May 5, 1973. The horse, also known as Big Red, was a champion American Thoroughbred racehorse who is the ninth winner of the American Triple Crowne.

Muhammad Ali reacts after his first-round knockout against Sonny Liston during the World Heavyweight Title fight at St. Dominic’s Arena in Lewiston, Maine on May 25, 1965. The match was one of the most anticipated, watched, and controversial fights in the sport's history, and this split-second shot by Leifer is considered to be one of the most iconic photos of the 20th century.