Logan Lerman Percy Jackson Brandon T. Jackson Grover Underwood Alexandra Daddario Annabeth Chase Douglas Smith Tyson Leven Rambin Clarisse La Rue Jake Abel Luke Castellan Katelyn Mager Young Thalia Grey Damon Chris Rodriguez Paloma Kwiatkowski Thalia Grace Anthony Stewart Head Chiron Stanley Tucci Mr. D / Dionysus Nathan Fillion Hermes Robert Maillet Polyphemus / Laistrygonian Ron Perlman Polyphemus (voice) Connor Dunn Tereus Alisha Newton Young Annabeth Bjorn Yearwood Young Grover Samuel Braun Young Luke Mary Birdsong Gray Sister #1 Yvette Nicole Brown Gray Sister #2 Missi Pyle Gray Sister #3 Anthony Shim Barista - Hecatonshire Shohreh Aghdashloo Oracle (voice) Craig Robinson George (voice)