The Swamp Thing is a humanoid/plant creature elemental, a humanoid mass of vegetable matter who fights to protect his swamp home, the environment in general, and humanity from various supernatural or terrorist threats. His real name is Alec Holland.
Alec Holland, a scientist working in the Louisiana swamps on a secret bio-restorative formula "that can make forests out of deserts". Holland is killed by a bomb planted by agents of the mysterious Mr. E, who wants the formula. Splashed with burning chemicals in the massive fire, Holland runs from the lab and falls into the muck-filled swamp, after which a creature resembling a humanoid plant appears some time later.
Meeting John ConstantineEdit
John Constantine first met Swamp Thing in 1985 after being interested with the creature. John later acts as the Swamp Thing's protector, guide, and voice of omen, even teaching the Thing to amplify his powers. Both would have further adventure with each other, such as John introducing the Thing to the Parliament of Trees, Thing using John's body to make love to his wife and father a child named Tefe, and fighting off the Damnation Army from summoning the Anti-Christ. Both carries a dull, but nevertheless fruitful friendship with each other. Constantine even invites Swamp Thing to his 40th birthday and assures the Thing he'll try not to bother him again. (Hellblazer issue 63)
The conclusion of the series Brightest Day revealed that Swamp Thing had become corrupted by the personality of the villain Nekron in the wake of the Blackest Night crossover. In the Brightest Day Aftermath: Search for the Swamp Thing, John Constantine tries to work out what has changed with Swamp Thing, and track him down, with the assistance of Zatanna, Batman and Superman. John managed to discover Alec Holland, who was now a normal human, and tries to get him back to being Swamp Thing, but Alec refuses.