The Man-Thing is a creature created by Stan Lee, Roy Thomas and
Gerry Conway, and featured in various Marvel Comics titles, the
most prominent of which was written by Steve Gerber.
Man-Thing is a large, slow-moving muck-monster with a vaguely humanoid
appearance living in the Florida Everglades near the Seminole reservation.
Man-Thing debuted a month before a one-shot version of DC Comics'
Swamp Thing, in which Alex Olsen was killed by his wife's lover
and resurrected as a plant-based monster. Swamp Thing creator Len
Wein was Conway's roommate at the time, but they did not discuss
their work too much. When the ongoing Swamp Thing, Alec Holland,
debuted in November (after Wein had contributed a Man-Thing story
of his own), his origin was very similar to Man-Thing's.
Unlike the intelligent Swamp Thing, Man-Thing is a former
scientist who became a nearly mindless mass of slime with no particular
affinity to any living thing, but who nevertheless often becomes
an accidental hero as it stumbles upon various crime and horror
scenarios. It is able to sense human emotions, and is enraged by
fear and automatically secretes a strong chemical corrosive; anyone
feeling fear and clutched by the Man-Thing is prone to be burned
(either chemically or mystically), hence the series' tag-line, "Whatever
knows fear burns at the Man-Thing's touch." Though fear is
understandably most people's response to the creature, typically
only villains end up meeting an immolating death at its hands.