Swamp Thing is a fictional character in the DC Comics Universe. He is a humanoid/plant elemental creature, created by writer Len Wein and artist Berni Wrightson. Swamp Thing has had several humanoid or monster incarnations in various different storylines. He first appeared in House of Secrets #92 (July 1971) in a stand-alone horror story set in the early 20th century. The character then returned in a solo series, set in the contemporary world and in the general DC continuity. The character is 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. ( thanks to wiki Dc )
Botanist Alec Holland became the avatar of the Green, known as the Swamp Thing, following his death in a swamp as a result of a horrific accident. With the ability to control any form of plant life, Swamp Thing uses his powers to protect both the human and the plant worlds. He works with Constantine and fights many supernatural creatures during his newer solo series. Most fans say that the marvel character Man-Thing is a copy of him.