10 Terrifying Batman: The Animated Series Episodes That Gave You Nightmares

Clayface as a character is just terrifying in general. He's a giant mass of muck with super-strength, and yet can move fast and vanish just as quick. That's without even going into the fact that he can change his shape to mimic anyone he sees as well.

There are two instances that really take the cake for scariest Clayface moment here. First, there is when Matt Hagen, the soon-to-be Clayface, returns from impersonating Bruce Wayne. The man he's working for is unsatisfied with Hagen's inability to kill Lucius Fox so he orders his men to kill him. Taking the inventive route, the two goons hold him down and begin to force the Renuyu - a chemical that alters facial features and a highly addictive substance - down Hagen's throat.

Though shown in shadows, the gargling screams as a man is forced into an overdose is demonstrably terrifying, and a testament to the show's willingness to bush boundaries.

Then after being put back into his car, still groaning and left for dead, Hagen's friend and stunt double finds him. Recoiling, the friend sees what appears to be clay all over his hands, before the body moves back and reveals a ghastly behemoth of clay screaming in agony.