A fullback (FB) is a position in the offensive backfield in American and Canadian football, and is one of the two running back positions along with the halfback. Typically, fullbacks are larger than halfbacks and in most offensive schemes their duties are split between power running and blocking for both the quarterback and the other running back. Many great runners in the history of American football have been fullbacks, including Marion Motley, Jim Brown, Jim Taylor, Franco Harris, Mike Alstott, Larry Csonka, John Riggins, Christian Okoye, and Marcus Allen.