Lenny is an English unisex name that originated as a diminutive form of Leonard, meaning "brave lion," or from the Irish surname O'Leary, meaning "descendant of Leary," derived from the Irish word for actor/storyteller. It gained popularity in the mid-20th century due to its association with notable figures like jazz musician Lenny Bruce and musician Lenny Kravitz, as well as its use in popular culture.