Cavill stars as Superman in Zack Snyder's "Man of Steel," out next June, while Hunnam stars in Guillermo del Toro's epic aliens vs. robots film "Pacific Rim," set for July. Skarsgård, of "True Blood" fame, had supporting roles in the likes of "Melancholia" and "Battleship" as well as a lead in the "Straw Dogs" remake. He also stars in the upcoming Toronto entry "What Maisie Knew," opposite Julianne Moore, and "The East," from "The Sound of My Voice" director Zal Batmanglij.
While Hardy has the most robust resume of these four, including "Bronson," "Warrior," "Inception," "The Dark Knight Rises" and "Lawless" -- he's yet to score big in a leading role. Depending on the intended tone of "Tarzan," his physicality could be just the thing for a rough and animalistic raised-by-apes hero. He will also star as Max in "Mad Max: Fury Road," and is rumored to be attached to Doug Liman's "Everest."