A polo neck, roll-neck (United Kingdom, South Africa), turtleneck (United States, Canada), or skivvy (Australia, New Zealand, United States) is a garment—usually a sweater—with a close-fitting collar that folds over and covers the neck. It can also refer to the type of neckline, the style of collar itself, or be used as an adjective ("polo necked").

A simpler variant of the standard polo neck is the mock polo neck (or mock turtleneck), that resembles the polo neck with the soft fold at its top and the way it stands up around the neck, but both ends of the tube forming the collar are sewn to the neckline. This is mainly used to achieve the appearance of a polo neck where the fabric would fray, roll, or otherwise behave badly unless sewn. The mock polo neck clings to the neck smoothly, is easy to manufacture, and works well with a zip closure.