Look up headliner in Wiktionary, the free dictionary.

The Headliner (or Headline act) at a concert event is the main band or performer at a concert, is most often the best known, and often performs as the final act in the lineup. Wikipedia does not have an article with this exact name. ... Wiktionary is a Wikimedia Foundation project intended to be a free wiki dictionary (hence: Wiktionary) (including thesaurus and lexicon) in every language. ... A classical music concert in the Rod Laver Arena, Melbourne. ... In music, a band is a group of musicians, or musical ensemble, usually popular or folk, playing parts of or improvising off of a musical arrangement. ... A classical music concert in the Rod Laver Arena, Melbourne. ...

Also known as first billing, both terms are derived from the prominent placement of the act's name on concert notices.

Compare to term Supporting act or Support act.