The Flash: 10 Best Villains (so Far)

Just four episodes into the show's second season, it introduced King Shark, who caught Barry off-guard, only to be subdued by Earth-2's Harrison Wells. Though he was only on screen briefly, the effects that brought the character to life were widely praised, and the mere fact he turned up at all served as an awesome reminder that the show has never been afraid to embrace its source material.

Though many figured it would cost too much to devote an entire episode to the character, King Shark returned anyway later in the season, breaking free from A.R.G.U.S. containment to once again hunt Barry down before, of course, being recaptured.

And while King Shark himself didn't have a whole lot in the way of characterization, he's simply one of the coolest villains the show has brought to life, and more than earns a spot on this list for those involved's willingness to make it happen.