Chaos Elemental

The Chaos Elemental is a Hardmode enemy that spawns on Pearlstone, Pearlsand and Pink Ice Blocks in the Cavern layer. It runs around and teleports quickly, attempting to damage the player by making contact. It will teleport anywhere in a random position within 20 tiles from its target, but at least 4 tiles away, and only into a space that is at least 4 blocks tall and 3 blocks wide. It will not teleport into lava, though it can easily fall into it after teleporting.

The also feature the exclusive Spectral Elemental variant.

Like many Underground Hallow enemies, Chaos Elementals have a glowing pink after-image.

Trivia

 * s are magical entities who embody/personify a force of nature. Historically, elementals personify one of the four Classical elements: earth, water, air or fire (sometimes plant, but never Aether). The fantasy tabletop role-playing game  introduced elementals that were fusions, and other unconventional elementals.