An SMA actuator (10) comprising SMA wires (31, 32) in which the wire arrangement is asymmetrical, allowing a greater range of motion from a rest position in a first direction than in a second direction, which may be opposite or orthogonal to the first direction. Where the directions are opposite, the angle between a principal axis and the wires providing motion in the first direction may be different from the angle between the principal axis and the wires providing motion in the second direction.