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 in size 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 of the great runners of the history of American football have been fullbacks, notably Jim Brown, Franco Harris, and Larry Csonka; in recent years the position has evolved to be more a blocker than a runner, with occasional pass-catching duties. While some teams have actually phased-out fullbacks altogether in favor of two tight end sets (notably, Indianapolis Colts have fullback spots filled by backup tight ends), the remaining prominent fullbacks in the NFL such as Ovie Mughelli, Leonard Weaver, Owen Schmitt and Tony Richardson are typically employed for breaking through tight defensive alignments, often in short-yardage situations as they are usually larger and heavier than halfbacks or tailbacks, or for screen passes. As a result, fullbacks are typically known less for speed and agility and more for muscularity and the ability to shed tackles. However, Le'Ron McClain was the rushing leader for the Baltimore Ravens in 2008, being deployed from the fullback position.
Although technically a running back, typically fullbacks are primarily valued for their blocking in most modern day offenses. In many offensive schemes, the fullback is used as a receiver, especially when the defense blitzes.
The position is less frequently used in Canadian football, which focuses more on passing than running the ball.