The viol (also known as the viola da gamba) is any one of a family of bowed, fretted and stringed musical instruments developed in the mid-late 15th century and used primarily in the Renaissance and Baroque periods. The family is related to and descends primarily from the Renaissance vihuela, a plucked instrument that preceded the guitar. An influence in the playing posture has been credited to the example of Moorish rabab players.

Viols are different in several respects from instruments of the violin family.