Assassin

The Assassin Medal is awarded for meleeing an opponent from behind. 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. After you kill an opponent by meleeing him in the back, a message appears on your screen that says: "You assassinated (player)". This is also a medal in the Halo 3 campaign in Campaign Scoring. It is a very common medal acheived in multiplayer.