Originally Alec Holland, a man who is transformed into a "muck encrusted mockery of a man" after an explosion in his laboratory doused him with chemicals (first appearance: Swamp Thing No. 1, Oct/Nov 1972: "Dark Genesis"; Note: The Alec Holland Swamp Thing is not the same character as the Swamp Thing first depicted in House of Secrets No. 92, Jun/Jul 1971: "Swamp Thing"). However, Swamp Thing later learns that he is actually an original being that has received the memories and self identity of Holland upon the man's death and is now a plant approximation of a humanoid being as a result (chronicled in The Saga of Swamp Thing No. 21, Feb 1984: "An Anatomy Lesson").
Originally, Swamp Thing has considerable strength and resistance to injury. However, upon discovering his true nature, he also learns that he can communicate with and control plant life as well as other numerous abilities related to plants.
In April 1979, Swamp Thing goes on a quest to change back from his swamp monster form to his human form. This mission brings him to the sewers of Metropolis to seek out Solomon Grundy in the hopes of experimenting on him and unlocking the secret of his horrid mutation (DCCP No. 8, Apr 1979: "The Six Deaths of Solomon Grundy!").
Swamp Thing finds Solomon Grundy battling Superman, so Swamp Thing teams up with Solomon Grundy to help him escape Superman's steel grip. Swamp Thing's experimentation on Solomon Grundy go awry as Grundy begins to multiply, leading to sixty Solomon Grundys running around rampaging through Metropolis. Superman decides to go to S.T.A.R. Labs to find a cure to Solomon Grundy's spawning problem. S.T.A.R. Labs gives Superman a special poison to eliminate the Solomon Grundy clones, which he uses on them—destroying them, and saving the day. Sadly, Swamp Thing can't help himself and must find a cure another day.
In September 1985, Clark Kent is covering a news conference by a scientist by the name of Dr. Everett, about a meteorite which was found with an alien fungus. After Clark Kent, who is secretly Superman, scans the fungus with his vision powers, he realizes that the fungus is from his home planet of Krypton. The fungus is the dreaded Bloodmorel, from the Scarlet Jungle of Krypton, which grows in blood and causes fever, hallucinations, overexertion, and in 92% of cases, death. Worst of all, Clark is infected. He realizes this when over the next few days he begins to lose his powers.
Coming to the horrible realization that he is dying, Kent purchases a secondhand car and starts driving southward along the I-55. Clark passes out while at the wheel of his car and crashes. Clark Kent manages to survive but then passes out yet again after experiencing hallucinations of the Scarlet Jungle of Krypton.
Swamp Thing finds Clark Kent but does not recognize him as Superman, until he notices Supermanâ€™s costume underneath Clarkâ€™s clothes. Swamp Thing makes contact with the fungus and discovers that it is an alien. Superman who was dreaming that he was in the Scarlet Jungle of Krypton fighting off its strange beasts, wakes up and still hallucinating attacks Swamp Thing with his powers. Swamp Thing realizes that Superman is dying and tries to save him, but Superman, suffering from the effects of the Bloodmorel, continues to attack Swamp Thing. Ultimately, Swamp Thing convinces Superman to calm down and relax, which allows Swamp Thing to heal Superman from his illness.
Swamp Thing then leaves Superman asleep in the forest. Superman awakens the next day and finds that he is fully healed and his super powers have returned. Superman grabs the meteor rock, which is now harmless and he flies away as Swamp Thing observes him leaving from afar (DCCP No. 85, Sep 1985: "The Jungle Line!").
Swamp Thing has appeared in the following Superman Stories
- DCCP No. 8, Apr 1979: "The Sixty Deaths of Solomon Grundy!"
- DCCP No. 85, Sep 1985: "The Jungle Line!"