Pacifist is an achievement in Halo: The Master Chief Collection. It is unlocked by completing The Silent Cartographer without firing a weapon, throwing a grenade, meleeing, dying or restarting. If playing co-operatively, both players must not shoot, grenade, melee, die or restart. The achievement is worth 10 gamerpoints and can be unlocked on any difficulty (though Easy is by far the best choice).
This achievement could be considered a replacement for the Grenadier achievement from the original Halo: Combat Evolved Anniversary, which unlike many other achievements from the game, does not reappear in The Master Chief Collection.