Assassin

The Assassin Medal is awarded and achieved for meleeing an opponent from behind the posterior of an unaware opponent. It is available in all Multiplayer gametypes and has a Bungie difficulty rating of 2 out of 10. It is represented by a ninja face on a shuriken star after you kill an opponent by meleeing the player in the back, a message appears on your screen that states: "You assassinated (player's name)". The Assassin Medal is also a medal in the Halo 3 campaign when Campaign Scoring is turned on and activated in the Meta Game. It is a very common achievement in multiplayer.

The victim can sometimes avoid this by turning around before the attacker has a chance to get a hit in, as it will count as a normal beatdown.