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 and Halo 4 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.


Earning a Killjoy on a Halo 3 Mythic map will unlock the Awww, Too Bad achievement.

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.