Flint Marko was a petty crook before Justin Hammer took him in and experimented on him, being one of the results of an attempt to recreate the Super Soldier Serum. Shortly after Hammer was killed by Dr. Octopus, S.H.I.E.L.D. infiltrated Hammer's factory to take care of any experiments Hammer had been working on. Marko used this opportunity to escape and wreak havoc upon New Jersey. S.H.I.E.L.D., with the help of Spider-Man, contained him and imprisoned him in a S.H.I.E.L.D holding facility.
Joining the Six
After the battle, S.H.I.E.L.D. sealed Marko in various jars and kept them frozen. 
Death of Spider-Man
Marko was, once again, freed by Norman and together they reformed the Six. Norman's intention this time, however, was to simply hunt down and murder Spider-Man. Marko agreed and the team went in search of Peter. After arriving at his house, they encountered the Human Torch and Iceman. They fought, and eventually the Six overpowered them. Spider-Man showed up and used water from a broken fire hydrant to soak them, causing Electro to short out and electrify the others. Shortly after, when Electro was shot by May Parker, he once again shorted out and electrified Sandman, knocking him out.
Powers and Abilities
Sand Conversion: Flint Marko can shift his DNA into an organic sand-like state, allowing him to alter his shape and size and become a living mass of sand. He can seep through small gaps, move like a sandstorm at high speed ripping through anyone in his path, or harden to a stone-like density.
He is not particularly confident in his control over his abilities.
- 17 appearance(s) of Flint Marko (Earth-1610)
- 1 minor appearance(s) of Flint Marko (Earth-1610)
- 1 mentions of Flint Marko (Earth-1610)
- 8 image(s) of Flint Marko (Earth-1610)
- 1 quotation(s) by or about Flint Marko (Earth-1610)