A hero (heroine is usually used for females) (Ancient Greek: ἥρως, hḗrōs), in Greek mythology and folklore, was originally a demigod, their cult being one of the most distinctive features of ancient Greek religion. Later, hero (male) and heroine (female) came to refer to characters who, in the face of danger and adversity or from a position of weakness, display courage and the will for self sacrifice—that is, heroism—for some greater good of all humanity. This definition originally referred to martial courage or excellence but extended to more general moral excellence.

Stories of heroism may serve as moral examples. In classical antiquity, hero cults that venerated deified heroes such as Heracles, Perseus, and Achilles played an important role in Ancient Greek religion. Politicians, ancient and modern, have employed hero worship for their own apotheosis (i.e., cult of personality).

Coined in English 1387, the word hero comes from the Greek "ἥρως" (heroes), "hero, warrior", literally "protector" or "defender" the postulated original forms of these words being *ἥρϝως, hērwōs, and *ἭρFα, Hērwā, respectively. It is also thought^{[citation needed]} to be a cognate of the Latin verb servo (original meaning: to preserve whole) and of the Avestan verb haurvaiti (to keep vigil over), although the original Proto-Indoeuropean root is unclear.