Anthony Head

The former "Buffy the Vampire Slayer" star replaces Pierce Brosnan, who played Chiron the centaur in the first film.

Fox 2000 has cast Anthony Head as Chiron in Percy Jackson & the Olympians: The Sea of Monsters.

A prolific U.K.-born television and film actor, Head is best known to U.S. audiences as Giles in the WB/UPN series Buffy the Vampire Slayer, which ran from 1997-2003. His recent credits include The Iron Lady and the television series Merlin.

EXCLUSIVE: Nathan Fillion to Play Hermes in ’Percy Jackson’ Sequel

Thor Freudenthal is directing Sea of Monsters, which will be released in 2013. Logan Lerman, Alexandra Daddario, Brandon T. Jackson and Jake Abel are returning in the lead roles.

The first title in the franchise, Percy Jackson & The Olympians: The Lightning Thief, grossed $226.5 million at the worldwide box office in 2010.

New additions to the film series based on Rick Riordan’s young-adult books include Nathan Fillion, who will play the god Hermes.

Chiron, a key character in Percy Jackson, is in charge of Camp Half-Blood, where demigods are trained and protected.

Head is repped by ICM.