Colossus is a Grimoire card from the original Destiny (Destiny 1), found under Enemies → Cabal. Grimoire cards held most of the game's lore and were read on Bungie.net and in the companion app, not in the game itself.
Card text
Towering over other Cabal, equipped with rapid-firing heavy weapons and nearly impenetrable armor, the Colossus is the most devastating heavy infantry unit in the Cabal order of battle.
Grimoire text written by Bungie, shown as it appears in the Destiny 1 game files.