The Thriller medal resembles a skull superimposed on a purple circular background on top of a six pointed silver star; it is awarded to individuals after killing 15 humans in a row without dying in Living Dead on Custom Games. The Thriller medal is the last of the infection spree medals in Halo: Reach. This medal can only be awarded on Living Dead.
- It is considered by many as one of the hardest medals in the game, and is currently impossible to get in Multiplayer Matchmaking, as well as the Mmmm... Brains medal. This is because there can only be a maximum of twelve players in an infection game, three of which start out as zombies. This leaves only nine humans left to infect; should you manage to infect all the humans by yourself, this still leaves you six kills short of the medal.
- This medal can only be unlocked with sixteen players, with one as the zombie.
- This medal is a reference to the song "Thriller" by Michael Jackson who dressed in makeup and clothes to make him look like a zombie when he sang this song.