A shuriken (Japanese 手裏剣; literally: "sword hidden in the hand") is a traditional Japanese concealed weapon that was generally used for throwing, and sometimes stabbing or slashing. They are sharpened hand-held blades made from a variety of everyday items such as needles, nails, and knives, as well as coins, washers, and other flat plates of metal.

Shuriken are commonly known in the West as "throwing stars" or "ninja stars", though they took many different shapes and designs during the time they were used. The major varieties of shuriken are the bō shuriken (棒手裏剣, stick shuriken) and the hira shuriken (平手裏剣, flat shuriken) or shaken (車剣, also read as kurumaken, wheel shuriken).