Grenadier is an achievement in Halo: Combat Evolved Anniversary that is awarded for completing the campaign level The Silent Cartographer on Heroic or higher without firing a weapon after accessing the Cartographer. It is represented by a plasma grenade outline over a golden six-pointed star.
The Achievement is worth 25 Gamerscore points.
A useful strategy when trying to unlock the achievement would be to activate the Bandana Skull, which will provide the player with unlimited grenades.
The name of the achievement is a reference to the fact that players can only defend themselves with grenades due to the requirements to get the achievement. While it is possible to melee, it would be very hard to do so. The player will need to get close to the enemy, which is virtually suicidal on higher difficulties.