SANDMAN

In The Amazing Spider-Man Vol. 1 #217 (1981), the Sandman and Hydro-Man — Morris Bench, a villain made of living water — first fought each other over barmaid Sadie Frickett, then teamed up against Spider-Man on a waterfront dock. When both men charged at once and Spider-Man leapt clear, sand slammed into water, the two forms mixed, and they plunged off the dock together. What climbed back out in The Amazing Spider-Man Vol. 1 #218 was neither man: a single hulking composite of wet sand and mud, soon dubbed the Mud-Thing, with the strength of both villains and the wits of neither.

The merged creature was slow, gentle, and fixated only on Sadie, and that made it valuable in the strangest possible way. A theater agent named Travis Rave put Sadie and the Mud-Thing on stage as a sideshow attraction, and attorney Matt Murdock even won a court ruling that the composite was a new being, not legally responsible for the crimes of either man inside it. The act ended when the creature rampaged, carried Sadie up a skyscraper, and was dried out by a special gas until it crumbled apart — and even then the story was not over, because the two villains stayed fused in the collected remains for months, only separating at last in Marvel Two-in-One Vol. 1 #86.

The strangest part is what the merge did to the Sandman afterward. Months trapped as half of a mindless mud monster became the turning point of his life: shaken by the experience, he began the long, genuine attempt to go straight that eventually carried him all the way to a presidential pardon and a place as a reserve Avenger. One of Marvel's oldest villains started becoming a hero because sand and water do not mix — and for a while, neither did he.