Helen, produced in 412, is a play in which the protagonists, Helen and Menelaus, pass from mortal danger in Egypt to escape and the promise of lasting happiness. For moderns a tragedy that ends happily is a contradiction in terms. But in Greek usage a tragôidia is a play about the figures of myth (unlike a komôidia, which is about the comic poet’s contemporaries), and any such play (apart from a satyr play, the burlesque on myth presented as the last play of a poet’s offering at the Dionysia) counts as a tragôidia. The chief requirement for a tragôidia is not that it ends in misery for the principals, but that it depicts the uncertainty of the mortal condition in …
Kovacs, David. "Helen". The Literary Encyclopedia. First published 13 July 2011; last revised 30 November -1.
[http://www.litencyc.com/php/sworks.php?rec=true&UID=13361, accessed 26 April 2015.]