Sasaki Kojirō (佐々木 小次郎, also known as Sasaki Ganryū) (1585? – April 13, 1612), often anglicized to Kojirō Sasaki, was a prominent Japanese swordsman widely considered a master of his craft, born in Fukui Prefecture. He lived during the Sengoku and early Edo periods and is most remembered for his death while battling Miyamoto Musashi in 1612.
Sasaki went by the fighting name of Ganryū (巌流, "Large Rock style"), which was also the name of the kenjutsu school he had founded. It is said that Sasaki studied the Chūjō-ryu of sword fighting from either Kanemaki Jisai or Toda Seigen.