Swamp Thing is the 1982 Embassy Pictures release of the independent, live-action feature film based on the DC Comics character of the same name created by Len Wein and Bernie Wrightson.
Adrienne Barbeau stars as Alice Cable (an amalgam of Matt Cable and Abby Arcane from the comics) who is sent to investigate an accident at a bio-lab that has killed researcher Alec Holland (Ray Wise). She discovers that the accident was caused by Anton Arcane (Louis Jourdan) and that Holland was transformed in the the titular creature, played by Dick Durock.
The movie was written and directed by horror-master Wes Craven (A Nightmare on Elm Street) and produced independently. It was a modest hit at the box office and enjoyed for its cheesy monster movie vibe.
Swamp Thing spawned a sequel call The Return of Swamp Thing and a follow-on TV series as well.