The shurikens, also known in the West as "throwing stars" or "ninja stars" are traditional Japanese concealed weapons that were 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.
The ninja stars are now the traditional projectile weapons for members of the diabolical ancient cult known as the Brotherhood of Shadows including Noob Saibot, Sub-Zero's dead older brother whose soul was corrupted because of the ordeal with the Brotherhood of Shadows' sacred treasure which belongs to their eternal master, the fallen Elder God Shinnok. Noob Saibot uses these in Mortal Kombat: Deception.
Reiko also uses these in Mortal Kombat 4 and Mortal Kombat Gold. In Mortal Kombat: Armageddon he throws several Shuriken one-by-one, his nearest (to the opponent) hand throws and the farthest hand holds the shuriken.
These mysterious weapons impale their victims with deadly accuracy, then vanish swiftly in a puff of smoke.
The shurikens later reappeared as collectible Relics under the name "Noob's Stars" in the Konquest mode of Mortal Kombat: Armageddon.
Cyber Sub-Zero uses a set of remote-controlled Shurikens in his second Fatality in Mortal Kombat (2011). He is able to command them to spin after being mounted inside his opponent, causing further damage.