Mac Curtis Speedie (January 12, 1920 – March 5, 1993) was an American professional football end who played for the Cleveland Browns in the All-America Football Conference (AAFC) and the National Football League (NFL) for seven years before joining the Saskatchewan Roughriders in Canada. He later served for two years as head coach of the American Football League's Denver Broncos. A tall and quick runner whose awkward gait helped him deceive defenders and get open, Speedie led his league in receptions four times during his career and was selected as a first-team All-Pro six times. His career average of 800 yards per season was not surpassed until two decades after his retirement, and his per-game average of 50 yards went unequalled for 20 years after he left the game.

Speedie grew up in Utah, where he overcame Perthes Disease to become a standout as a hurdler on his high school track team and a halfback on the football team. He attended the University of Utah, where he continued to excel at track and football before entering the military in 1942 during World War II. He spent four years in the service before joining the Browns in 1946, where he played as an end opposite quarterback Otto Graham, fullback Marion Motley and fellow receiver Dante Lavelli. The Browns, a new team in the AAFC, won the league championship every year between 1946 and 1949. The Browns merged into the NFL in 1950 after the AAFC disbanded, and Speedie continued to succeed as the team won another league championship. After two more years with the Browns, however, Speedie left the team for the Western Interprovincial Football Union (WIFU) amid a conflict with Paul Brown, Cleveland's head coach. He played two full seasons in the WIFU and one game in a third season before leaving professional football.

Speedie was hired in 1960 as an end coach for the Houston Oilers in the American Football League (AFL). The Oilers won the AFL championship that year, but Speedie left in 1961 after the head coach, former teammate Lou Rymkus, was fired. He then took a job as an assistant for the AFL's Denver Broncos and was promoted to head coach in 1964. His two-year run with the team was unsuccessful, however. After his resignation in 1966, Speedie became a scout for the Broncos, a job he kept until his retirement in 1982. He was inducted into the Pro Football Hall of Fame of 2020.

Speedie was born in Odell, Illinois, but attended high school in Utah. As a child he had Perthes Disease, a condition where growth or loss of bone mass in the hip joint affects blood supply to the area. He had to wear a brace for four years to correct the condition; one of his legs came out shorter than the other. Despite his struggle with the disease, Speedie became a star athlete at South High School in Salt Lake City, playing football, basketball and track. He was the center on the school's basketball team and was named to a list of Salt Lake's best athletes as a halfback on the football team. Getting out of the braces "was like turning a frisky colt out to pasture after a year in a box stall", Speedie once said. "I had such a backlog of athletic ambition that I wanted to play football, basketball, and track all at one time."

After graduating from high school, Speedie attended the University of Utah, where he majored in geology and continued to excel as an athlete. He played football and basketball and was a top college hurdler in track. As an end on the Utah Redskins football team, he won all-conference honors in 1939, 1940 and 1941. In track, he finished second in a high hurdles event where the winner, Rice University's Fred Wolcott, set an NCAA record.

Like many college athletes, Speedie joined the military as America's involvement in World War II intensified following the attack on Pearl Harbor at the end of 1941. He entered the U.S. Army after graduating in 1942. Speedie was stationed at Fort Warren in Wyoming and played for the base's Broncos military team.

Speedie was drafted by the National Football League's Detroit Lions in the late rounds of the 1942 draft. Fred Mandel, the owner of the Lions, visited him at Fort Warren and offered a contract worth $2,800 a year. Speedie wanted to sign immediately, but Mandel preferred to wait until after the war. By the time the war drew to a close in 1945, however, Speedie was considering signing with the Chicago Rockets, a team in the new All-America Football Conference (AAFC). He was pursued by the Rockets after playing well against a team at Marine Corps Air Station El Toro from which many of the Rockets' players were drawn. Speedie was also spotted by Paul Brown, who had been the head coach of a military team at Great Lakes Naval Station that played against the Broncos. Brown, who was starting a new AAFC team called the Cleveland Browns, sent a friend named Jackie Ranen to sign Speedie for $7,000 in 1946.

With the Browns, Speedie quickly became an important part of an offensive attack that featured quarterback Otto Graham, fullback Marion Motley and fellow receiver Dante Lavelli. He was enthusiastic, energetic and fast, posing a challenge for defenders assigned to cover him. He had an unusual running style because of his bout with Perthes Disease, which Lavelli said "gave him an odd gait in which he could fake plays without even trying". Speedie caught the first touchdown in the AAFC's existence in the Browns' opening game against the Miami Seahawks, a 44–0 win. The Browns ended the regular season with a 12–2 record, winning the AAFC West division and earning a spot in the league championship. During the week before the championship game against the New York Yankees, Speedie and two teammates, Lou Rymkus and team captain Jim Daniell were arrested after an argument with Cleveland police. Daniell was driving a car with Rymkus and Speedie as passengers as they waited for Speedie's wife to return on a flight from Utah. A police car was blocking Daniell's way, and he honked the horn, leading to the confrontation and arrests. Brown kicked Daniell off of the team, but Speedie and Rymkus were not punished by the team; they were, however, held in custody for several hours and charged with creating a disturbance.