King of the Lapithae and friend of Theseus, on the occasion of whose marriage an intoxicated Centaur ran off with his bride Hippodamia, which gave rise to the famous fight between the Centaurs and the Lapithae, in which Theseus assisted, and the former were defeated; on the death of Hippodamia, Pirithous ran off with Persephone and Theseus with Helen, for which both had to answer in the lower world before Pluto; Hercules delivered the latter, but Pluto would not release the former.