OST is the name of several artists. 1) a Basque metal band
2) an experimental/math/atmospheric musician based in Ireland, OST - Original Soundtrack
3) a variation on Old School Tie
4) a variation on O.S.T.
5) a variation on Robbie Ost
6) a variation on Oswald Berthold
7) an alias of Petter Haavik It may also be an incorrect artist tag for a soundtrack, if so do yourself and Last.fm a favour and fix your tags.