Hopkins will play Odin, the father of Thor and Loki, played by Chris Hemsworth and Tom Hiddleston, respectively. Portman will be playing Thor's love interest, Jane Foster.
Written by Mark Protosevich and Zack Stentz, Thor focuses on a partially disabled medical student's discovery of his Norse god alter ego, the hammer-swinging Thor.
Among Hopkins' stage credits include Pravda and King Lear in the U.K. and Equus on Broadway. Portman appeared on Broadway in Diary of Anne Frank and in the Shakespeare in the Park production of The Seagull.