The Geth Colossus is a massive ground-based Geth assault platform that appears in Mass Effect. It is a larger and stronger version of the Geth Armature.
Colossi are distinctive from Armatures because their armour is brighter, somewhat platinum-silver in appearance, with ridges on the back. They are equipped with mass accelerator machine guns and a powerful Siege Pulse mass accelerator cannon. Their weapons can make short work of infantry and their armour and shields are too strong to penetrate with standard armaments. However, Colossi are seldom encountered when the player does not have the M35 Mako vehicle available. The Mako's machine gun can slowly whittle away a Colossus' shields and its heavy cannon can cause partial damage even when the shields are still up. Distance and precise aim are essential when battling a Colossus. Since the Colossus' defences are so strong, do not expect a short fight, unless you're on the losing end of it.