- Gerard Horan appeared in March 2002 in Sheffield, England as the Duke of Clarence in Kenneth Branagh's Richard III at the Crucible Theatre.
- (2002) He acted in William Shakespeare's play, "Richard III," at the Crucible Theatre in Sheffield, South Yorkshire, England with Kenneth Branagh, Danny Webb, Robert Demeger, Barbara Jefford, Michael Jenn, Richard Durden, Avril Elgar, Claire Price, Phyllis Logan, Robert East, Gideon Turner, and William Rycroft in the cast. Michael Grandage was director.
- (1984) He acted in Edward Bond's plays, "The Pope's Wedding," and "Saved," at the Royal Court Theatre in London, England with Peter Hugo-Daly, Adrian Dunbar, Gary Oldman, Lesley Manville, and June Watson in the cast. Max Stafford-Clark and Danny Boyle were directors.
- (1989) He acted in John Osborne's play, "Look Back in Anger", at the Lyric Theatre in London, England with Kenneth Branagh, Emma Thompson, Siobhan Redmond and Edward Jewesbury in the cast. Judi Dench was the director.
- (2009 - 2010) Starred as Wesley in Jerusalem by Jez Butterworth (2012) Starred as Charlie Clench in One Man Two Guvnors