He's been in 2 different movies, had his own show on the USA NETWORK, and even his own brief Saturday Morning cartoon. But what made SWAMP-THING one of the more incredible monsters was his wonderful comic book.
In 1971, Len Wein and Bernie Wrightson put together a small 8 page story for HOUSE OF SECRETS #92 of a man named Alex Holland who was madly in love with his wife, but a tragic accident in his lab and his burial in the bog caused him to be resurrected as THE SWAMP-THING. He saved his wife from his evil former partner, but when she saw the muck encrusted monstrosity that used to be her husband, she wasn't thankful...she could only scream.
The tragic last page, referenced above, sets the tone for the eventual monthly SWAMP-THING comic. Everyone thinks he's dead, he can barely talk, and anyone he approaches runs away in fear. Not to mention every wacko swamp creature and mutant out there wants to kill you know.
Such is the life of SWAMP-THING. The book was canceled after 23 issues, but the first 8 issues by Wein and Wrightston are about as good as comic books get.
In 1982, Wes Craven wrote and directed a SWAMP-THING movie. Though a bit silly, the film was relatively true to the comic, and featured lovingly long shots of Adrienne Barbeau's magnificent breasts throughout. And for some strange reason, it even spawned a sequel, with Heather Locklear.
After the comic series came back for a second run in the late 80s, legendary writer Alan Moore took a crack at it and reinvented SWAMPY as a godlike plant elemental who was one with the world's vegetation (and CUBS fans).
The SWAMP-THING cartoon.