Thought to be a wizard-bred creature to protect treasure, Acromantulas are native to Southeast Asia, and are social creatures who live in large colonies, with the oldest male and female leading the colony. Their natural and most hated enemy is the Basilisk; Acromantulas have many eyes, and basilisks killed with their gaze, making Acromantulas very susceptible.

Acromantulas are capable of human speech, and typically grow to 15 feet in size. They also produced a toxic venom which was rare and valuable. Acromantula eggs were a Class A Non-Tradeable Good.

One of the Acromantulas in the Forbidden Forest was named Aragog, who was raised by Rubeus Hagrid in a cupboard from an egg. Aragog formed a close attachment to Hagrid, and with the complete control of the colony as its leader, Aragog was able to protect Hagrid from being eaten. Aragog ruled the colony with his wife, Mosag, until his death in 1996. The colony participated in the Battle of Hogwarts, attacking both sides after being driven out of the forest by Death Eaters.