From Halopedia, the Halo wiki

This article is about the medal. For the Halo Wars achievement, see Killjoy (achievement).
Killjoy Halo 3 Medal Icon

Killjoy is a medal awarded in Halo 3, Halo: Reach, Halo 4, and Halo Infinite multiplayer for killing a player who is on a Killing Spree of five kills or higher. It is represented by an octagon with a crossed-out smiley face in the middle.


  • In the Halo 3 multiplayer beta, the medal is depicted by a yellow-outlined octagon with an orange interior and a black silhouetted Master Chief, based on Halo 2's concept art.
  • Prior to the shutdown of Xbox 360 Halo online services on January 13, 2022, earning a Killjoy on a Halo 3 Mythic map would unlock the Awww, Too Bad achievement.
  • Earning 250 Killjoy medals in Halo: The Master Chief Collection multiplayer matchmaking will unlock the Party Pooper achievement.