副翼（法语：Aileron）是固定翼飞机机翼后缘上一对对称的操纵面，用以控制飞行器的滚转运动。副翼通过左右差动偏转在两侧机翼上造成升力差，并且产生滚转力矩。由于固定翼飞行器的滚转轴运动和航向轴运动耦合，副翼结合升降舵也可以用来控制飞机的航向运动。因此是一种非常重要的操纵面。现今大多数固定翼飞行器上都具有副翼。

副翼是英国工程师马修·瓦特·博尔顿（Matthew Piers Watt Boulton）发明的。他在1868年根据自己的论文申请了第一个副翼的专利。副翼的拉丁名“Aileron”来自法语，意为“小翼”。

An aileron (French for 'little wing') is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around the aircraft's longitudinal axis), which normally results in a change in flight path due to the tilting of the lift vector. Movement around this axis is called 'rolling' or 'banking'.