From Halopedia, the Halo wiki
It is represented by a bronze five-pointed star with a green MJOLNIR helmet with outward-pointing spikes.
- This medal is very hard to achieve in Halo 3's Matchmaking because Juggernaut matches only go up to 10 kills. Killing the Juggernaut to become one will add a point to a player's score, but since he/she was not the Juggernaut at the beginning of the game, it will not count as one of the 10 kills needed for the medal.
The remodeled version in Halo: Reach.