20 Greatest Spider-Man Villains Ever
10. Sandman
Flint Marko had a heck of a bad day. While on the run from the law, he fled to a nuclear testing site and came in contact with some irradiated sand. Just like in the real world, this turned him into a pile of sentient sand.
Sandman's shapeshifting abilities make him a difficult foe to fight and Spider-Man has often had to resort to creative measures such as turning him to glass or isolating the single grain that contains his consciousness.
He is also quite a tragic figure, his numerous attempts to reform always ending in failure. For a time he was even an Avenger before he slid back into villainy.