The Swamp Thing was a scientist who was mutated into a swamp-like creature. He is voiced by Mark Hamill.
Once a scientist living in a swamp Alec Holland was attacked by criminals who used explosives to kill him, instead his body fell into the swamp where he was reborn as a creature of living vines, grass and moss. A new champion for the Green Alec Holland became Swamp Thing, a protector of the natural world but and outcast to humanity due to his freakish form. He joined the Justice League during the crisis with the Brothers Djinn and became a member,fighting to protect the world. Swamp Thing had a run in with Solomon Grundy who sought to raise and army of the dead to rule the world, but with help from Batman and Zatanna he put an end to Grundy's plans and save the city of New Orleans.