Marcus LeMarr Allen (born March 26, 1960 in San Diego, California) is a former American football player , and until recently affiliated with CBS as a game analyst. As a professional, Allen ran for 12,243 yards and caught 587 passes for 5,411 yards during his career for both the Los Angeles Raiders and the Kansas City Chiefs from 1982 to 1997. He scored 145 touchdowns including a then league record 123 rushing touchdowns and was elected to six Pro Bowls when he retired. He was also a fairly good passer for a running back, completing 12 of 27 passes for 285 yards and 6 touchdowns, with only 1 interception. Allen was the first player ever to gain more than 10,000 rushing yards and 5,000 receiving yards during his career.

Allen is considered as one of the greatest goal line and short-yardage runners in National Football League history. He was inducted into the College Football Hall of Fame in 2000 and the Pro Football Hall of Fame in 2003. He is the older brother of Damon Allen, who plays in the Canadian Football League.

Marcus Allen is the British distributor and publisher of Nexus magazine, and a well known proponent of, as he puts it, "news and information that is overlooked, unreported or ignored by the mainstream media." He worked as a photographer in the 1960s, and is a proponent of the idea that NASA faked the Apollo Moon landings.