A peg leg is a prosthesis, or artificial limb, fitted to the remaining stump of a human leg, especially a wooden one fitted at the knee. Its use dates to antiquity.

By the late 19th century, prosthetics vendors would offer peg legs as cheaper alternatives to more intricate, lifelike artificial legs. Even as vendors touted advantages of more complicated prostheses over simple peg legs, according to a contemporary surgeon, many patients found a peg leg more comfortable for walking. According to medical reports, some amputees were able to adjust to the use of a peg leg so well that they could walk 10, or even 30, miles in one day.

Nowadays, wooden peg legs have been replaced by more modern materials, though some sports prostheses do have the same form.