Slimer

Slimer is a Hardmode enemy that only spawns in The Corruption and Underground Corruption. It starts off as a flying ball of slime, and when "killed" the first time it loses its wings and becomes a groundborne slimer. Slimers are actually two kinds of enemies put together, half bat, half slime, therefore they have two sets of health.

Slimer is immune to the Poisoned debuff.

Trivia

 * The wings on the first form of Slimer are almost, if not an exact, look-a-like to Demon Wings.
 * Winged version not only can fly but also swim in water (unlike ordinary slimes that float on the surface).