The Acromantula is a fictional creature created by J.K. Rowling for the Harry Potter series of books. It takes the form of a massive poisonous spider with eight eyes. Acromantulas are covered in thick black hair; they have legspans of up to fifteen feet, as well as giant pincers.

Acromantulas, particularly their leader Aragog, are encountered in Harry Potter and the Chamber of Secrets by Harry and his friend Ron Weasley. They are carnivores which prefer large prey. Their webs are large and dome-shaped and the female, which is bigger than the male, may lay up to one hundred soft, wide, beach ball–sized eggs at a time, which hatch in six to eight weeks. The Ministry of Magic has imposed severe penalties for the trade of these eggs.

Acromantulas are believed to be wizard-bred, possibly to guard dwellings or treasure, and are therefore possessed of the power of human speech and near-human intelligence. They are, however, totally untrainable and gain a five-X Ministry of Magic rating.