'antihero' originates from the prefix 'anti-' (from Greek 'antí') meaning 'against' and 'hero' (from Greek 'hērōs') meaning 'hero'; the compound was formed in English in the 19th century.

'antihero' was originally written as the hyphenated form 'anti-hero' and later also found as the solid form 'antihero' in modern English usage.

Initially the element 'anti-' indicated opposition to the idea of a traditional hero; over time the term came to refer specifically to a protagonist who lacks traditional heroic qualities and may be morally ambiguous.