From Destinypedia, the Destiny wiki
Thrall are the most common morph of Hive. Their main purpose is to overwhelm their enemies with sheer numbers, although individually they are easily dispatched. Feral and fearless, Thralls are a plague upon the battlefield.
Thralls are born from pupae laid by fertile Wizards. Upon hatching, they are fed a larval worm which enters into a symbiotic relationship with the Thrall. If a Thrall is able to fight and survive well enough, it will become an Acolyte. Otherwise, the worm will consume it from within.
While individually Thrall are the weakest Hive enemy, in large enough groups they can be deadly especially if they are supported by other Hive enemies with heavy weaponry.
With their sharp claws as their primary tools of attack, Thralls move quickly and in large packs to overwhelm their enemies.
List of appearances