Santa-NK1

Santa-NK1 (also known as Santank) is a boss that makes an appearance during the Frost Moon. It acts similar to Mourning Wood, often chasing the target before stopping after a time to unleash one of three attacks.

When below half health, the face and beard of the Santa mask will be torn apart to reveal a rather deathly skull underneath.

Trivia

 * "Santa-NK1" is actually a play on the word "Santank", the name used when the Santa-NK1 was announced. Santa-NK1 -> Santa-nk1 -> Santank1 -> Santank -> Santa Tank
 * "Santa-NK1" Is also a reference to Santa Claus Origin name Saint Nick. NK1 = Nick.
 * Santa-NK1 might be a reference to Robot Santa Claus in Futurama.
 * Santa-NK1's arm would appear to be the chain gun
 * Santa-NK1 has the fourth highest defense of all enemies in the game - fourth only to the Dungeon Guardian, Blazing Wheel, and Spike Ball, and those three aren't really meant to be destroyed.
 * Santa-NK1 may also be a reference to the Metal Slug franchise, created by SNK.