Tackle is a playing position in gridiron football. Historically, in the one-platoon system prevalent in the late nineteenth and early twentieth centuries, a tackle played on both offense and defense. In the modern system of specialized units, offensive tackle and defensive tackle are separate positions, and the stand-alone term "tackle" refers to the offensive tackle position only. The offensive tackle (OT, T) is a position on the offensive line, left and right. Like other offensive linemen, their job is to block: to physically keep defenders away from the offensive player who has the football and enable him to advance the football and eventually score a touchdown. The term "tackle" is a vestige of an earlier era of football in which the same players played both offense and defense.

A tackle is the strong position on the offensive line. They power their blocks with quick steps and maneuverability. The tackles are mostly in charge of the outside protection. Usually they defend against defensive ends, but they do also have to defend against defensive tackles, especially if the corresponding guard on their side pulls. In the NFL, offensive tackles often measure over 6 ft 4 in (193 cm) and 300 lb (140 kg).

According to Sports Illustrated football journalist Paul "Dr. Z" Zimmerman, offensive tackles consistently achieve the highest scores, relative to the other positional groups, on the Wonderlic Test, with an average of 26. The Wonderlic is taken before the draft to assess each player's aptitude for learning and problem solving.

The distinction between right and left tackle has become less relevant.