Counterparts to the Grey Slayers, the Grey Stalkers served to complement their raw and savage fury with more focused rage and varied equipment. Their role in battle was akin to that of traditional Tactical Squads, but molded by Leman Russ into something new and distinct. In battle, they followed in the wake of Grey Slayers to harry foes too well entrenched for a frontal assault and securing objectives cleared by the initial onslaught.
The Grey Stalkers were often composed of disproportionately high amounts of Terran recruits, for they behaved in the manner similar to the Legion before the coming of Russ. Its members saw themselves less tied to the rites and culture of Fenris, but many Fenrisian Marines viewed them as lacking in zeal.
Grey Stalkers were normally equipped with Bolt Pistols and Chainswords, but could be equipped with a wide array of Astartes weaponry such as Bolters, Flamers, Volkite Chargers, Plasma Guns, Melta Guns, Rotor Cannons, Power Weapons, etc.