This one seems obvious, but the creators of each character insist they were just doing their own thing. DC and Marvel, within two months of one another, each concocted a feared and misunderstood creature; half man, half monster; spawned in the swamp. But this one goes to Marvel - by a nose: Man-Thing premiered in May 1971, in Savage Tales #1; Swamp Thing debuted in House of Secrets #92, in July 1971. Both characters were scientists working on a drug for the government; both suffer a mishap and end up being fused with swamp muck. There was one big difference, though: Marvel called their creation Man-Thing, while DC called theirs Swamp Thing. Hey, you can never be too subtle. Stan Lee, who'd recently been promoted to publisher at Marvel, called his pal Carmine Infantino, who'd recently been promoted to publisher at DC (not sure who was copying who with these career moves) and threatened to sue him. Carmine laughed and reminded Stan that the origins of both their muck monsters were rooted in a character called the Heap, published in 1942 by Hillman Periodicals. Legend has it that after their phone call, these two highly competitive comic book pioneers met for lunch.