Hoppin' Jack

The Hoppin' Jack is a Hardmode pumpkin-like enemy that will only appear at night during the Halloween seasonal event. It attacks by hopping towards the player in a manner identical to most Slimes.

Notably, despite using the Slime AI, it is not treated as a slime for most other purposes. Hoppin' Jack drops no Gel on death, will remain hostile to a player with Royal Gel equipped, and killing one is not necessary to earn the Gelatin World Tour or Slimer  Achievements.

Trivia

 * The name Hoppin' Jack is a reference to a creature from British folklore.