Frankenstein

The Frankenstein is a Hardmode enemy that spawns only during a Solar Eclipse, during which they are as common as zombies. Hitting much harder, having more life and walking faster, they can be considered "super-zombies".

They are one of only two (the other being Swamp Thing) enemies that drop the Broken Hero Sword, which is necessary for crafting the most powerful sword in the game.

Trivia

 * Frankenstein is a reference to the namesake 1931 film, as the theme of Solar Eclipse enemies is classic horror film icons.
 * Terraria propagates the a common misconception that Frankenstein is the name of the monster rather than the doctor who created it.