Collector Drones are the most common type of Collector encountered in Mass Effect 2 and in Mass Effect 3's multiplayer expansion Retaliation. They appear as bio-mechanical humanoid insects with bodies covered in chitinous skin and their heads are elongated at the back. They also have four eyes .
Drones are the basic Collector soldiers and servants. They are armed with assault rifles loaded with warp ammo that disrupts shields and biotic barriers. They have insectoid wings on their backs and use them to fly onto the battlefield, although they are never shown attacking whilst in the air.
- Guardian - Drones reinforced with biotic barriers. They carry assault rifles that fire in bursts and can also plant Hex Shield barriers to block enemy fire.
- Trooper - Armed with SMGs and frag grenades. Also known to use organic blades in close-range combat.
- Assassin - Reinforced with biotic barriers and armed with particle beam rifles.
- Possessed - At any time during combat, Harbinger can possess a Collector Drone on the battlefield. The possessed Drone appears to glow and burn from the inside and becomes much stronger in this state. It is surrounded by a biotic barrier and its skin becomes armoured. It does not react to attack or injury and continuously advances on the enemy whilst firing blasts of dark energy and incendiary pulses. When a possessed Drone is killed, its body disintegrates into dust. Of course, as long as there are any Collectors remaining on the battlefield, Harbinger can always seize control of another.