hero: [14] Hero is a Greek word – hérōs – applied in ancient times to men of superhuman ability or courage, and in due course by extension to demigods. At first it was used in English simply to render this Greek notion, and it was not until the late 16th century that the extended and more general sense ‘brave or otherwise admirable man’ began to emerge. ‘Chief character in a story’ is a late 17th-century development.
English acquired the word via Latin hērōs as heros, but it was not long before this became interpreted as a plural, and a new singular hero was formed. Heroin [19] comes from German heroin, said to have been coined from the delusions of heroism which afflict those who take the drug. => heroin[hero etymology, hero origin, 英语词源]