The free safety is one of four positions in the defensive secondary region (also known as the defensive backfield) of American and Canadian football. This player tends to be smaller and faster than the strong safety, his counterpart on the secondary. His job tends to be to keep some distance from the line of scrimmage, watch the play unfold, and follow the ball. The free safety would correspond to the quarterback in man coverage, but as the quarterback usually remains in the pocket the free safety is "free" to double cover another player. On pass plays, the free safety is expected to assist the cornerback on his side and to close the distance to the receiver by the time the ball reaches him. Offenses tend to use the play-action pass specifically to make the free safety expect a run play, which would draw him closer to the line of scrimmage, and reduce his effectiveness as a pass defender. Furthermore, quarterbacks often use a technique to "look off" a free safety, by purposely looking to the other side of the field during a pass play, with the intention to lure the free safety away from the intended target receiver on the other side of the field. This phenomenon often tests how effective a free safety's wit and athleticism is at defending long pass plays. If the offense puts a receiver in the slot, then the free safety may be called upon to cover that receiver. Free safeties occasionally blitz as well. When this happens, the pressure on the quarterback is often very severe since a blitz by a defensive back is not usually anticipated. Free safeties, because of their speed and deep coverage, are often prone to catching interceptions. Standout retired free safeties include Paul Krause, Larry Wilson, and Willie Wood. Ed Reed and Nick Collins are the most notable currently active free safeties.

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