The Man-Thang first appeared in an issue of Cabbage Tales, soon after the publication of Dee-See's House of Sucrets #94 which was the debut of Swamp-Thang, a character with a similar origin. As the publications dates were too close, none of the companies would have been able to get inspiration from the other, but the characters themselves still had a grudge about each of them having seen its origin story "stolen" by the other.
An empathic creature, the Man-Thang spent some time with a pet, Raoul the male alligator - who was a bad influence for the Man-Thang, because Raoul cared only about his next meal, conditioning the emotions that the Man-Thang felt. While the Man-Thang spent most of its time in the Swamp, other Marble Universe characters were familiar with him and his lack of personality. Maybe it was because sometimes the Man-Thang left the Swamp and visited other places with many superheroes. The Man-Thang was seen protuding from a trash can when Superbman prepared to fight the Fantastical Four near their city headquarters.
Adventures into Fear!
The Man-Thang returned to his swamp and saw a number of people who did not interest him. A babe in distress appeared, screaming and scantly-clothed, and the Man-Thang followed her. Recognizing the Man-Thang as a potential person, she asked him for help: her ex-boyfriend, the Swamp-Thang, was stalking her. Swamp-Thang appeared speaking about flower power, but she claimed to not want to go back with him, instead staying with the mouthless Man-Thang. The Swamp-Thang agreed to leave.
But the angry Man-Thang stopped the Swamp-Thang. He vainly tried to communicate with the Swamp-Thang with charades, and then used a sign to blame him for stealing his origin. The Swamp-Thang tried to explain, but they were in a Marble Comic and the fight scene was mandatory: the Man-Thang punched through the Swamp-Thang's head. The Swamp-Thang then broke the Man-Thang vertically in half. That did not stop either, and they fought until they ended intermingled. Finally, the Swamp-Thang started burning because he was overwriting, breaking the Man-Thang's taboo.
However, when the babe saw her ex-beau badly injured, she took pity on him and agreed to go back with him to the AC Universe. The Swamp-Thang agreed the conditions and told the Man-Thang that he felt no anger because he was back with his status quo. The Man-Thang left and submerged in the swamp, taking a last sign to tell the narrator to shut up.
The Man-Thang then took the nickname of Man-Thing and was next seen in the TV "Super Villain Dating Games", hosted by Jim Lame and with beautiful Trixie LaRue as the contestant. Man-Thang was bachelor number three and, being mute, was unnable to answer Laure's questions - this impressed Laure, who envisioned him as the "strong silent type" and chose him. The Man-Thing stood and walked to get some kisses from Laure, but she was scared as heck and tried to run away. Meanwhile, Lame insisted she should not get nervous or she may get burned.
For reasons unclear, the Man-Thing, now known as the Man-Thank (you're welcome), ended up in a pot of vegetable food served by the Hicks-Men clan of the Ozarks of Missouri. They intended to impress their new guest the Bulk (aka Ben Grimm) serving him some food but, when they dropped the pot on the table, the Man-Thank silently walked from it and left through the door. The Bulk decided he did not want to eat food where the Man-Thank had been swimming and tried to leave too.
Powers and Abilities
Burn: Following a traditional mantra, whatever knows overwriting burns at the touch of the Man-Thang. Other acception suggest that is whover knows fear, or first date jitter, who burns at its touch.
Camouflage: As he looks like most of the swamp, many people and animals walk next to him in the swamp, ignoring him, and vice versa.
Empathy: The Man-Thank is an empath who absorbs the emotion of nearby beings, sometimes (he does not seem to absorbe the Swamp-Thang's hippie attitude, but he absorbed his lets-get-drunk attitude)
Resistance: The Man-Thank can withstand a lot of physical punishment: He can even be broken in half, and simply reconstruct.
Signs: The Man-Thank can get signs with letters on it from the inside of his body. This is his main form of communication.
Strength: A punch of the Man-Thank can go through the head of the Swamp-Thang. Not that that damages Swamp-Thang a lot.
His trunk is a manipulative appendage.
The Man-Thank cannot speak, move or think in the traditional sense of the word. He has no personality either. Although mute, he can communicate with signs taken from the inside of his body because - he is really bad at charades!