Pierce Brosnan and Uma Thurman cast as gods in “Percy Jackson” Pierce Brosnan and Uma Thurman have been cast as Greek gods in fantasy-adventure “Percy Jackson” The script, by Columbus and Craig Titley, is adapted from Rick Riordan’s children’s book The Lightning Thief. It involves Percy, the half-human son of Poseidon who attempts to prevent a war erupting between the gods in present-day America. Brosnan will play Chiron and Thurman will play Medusa. Other actors involved include Sean Bean (as Zeus), Kevin McKidd (as Poseidon) and Melina Kanakaredes (as Kanakaredes). is still searching for actors to play Aries, Hades and Persephone.