Logan Lerman as Percy Jackson

Brandon T. Jackson as Grover Underwood

Alexandra Daddario as Annabeth Chase

Douglas Smith as Tyson

Leven Rambin as Clarisse La Rue

Jake Abel as Luke Castellan

Katelyn Mager as Young Thalia

Grey Damon as Chris Rodriguez

Paloma Kwiatkowski as Thalia Grace

Anthony Stewart Head as Chiron

Stanley Tucci as Mr. D / Dionysus

Nathan Fillion as Hermes

Robert Maillet as Polyphemus / Laistrygonian

Ron Perlman as Polyphemus (voice)

Connor Dunn as Tereus

Alisha Newton as Young Annabeth

Bjorn Yearwood as Young Grover

Samuel Braun as Young Luke

Mary Birdsong as Gray Sister #1

Yvette Nicole Brown as Gray Sister #2

Missi Pyle as Gray Sister #3

Octavia Spencer as Martha (voice)

Christopher Redman as Reardon

Jordan Weller as Ichneutae

Camille Atebe as Harpy Barista

Anthony Shim as Barista - Hecatonshire

Robert Knepper as Kronos

Richard Yearwood as Ganymede

Derek Mears as Cyclops #1

Aleks Paunovic as Cyclops #2

Maxine Miller as Parcel Store Customer

Shohreh Aghdashloo as Oracle (voice)

Craig Robinson as George (voice)