Beast Complex (stylized in all caps) is a Japanese manga series written and illustrated by Paru Itagaki.

The stories take place in a modern world occupied by anthropomorphized animals of various species.

The doujinshi introduced characters and setting elements (such as a war resulting in the illegalization of meat and the creation of a black market to sell it) that would be reused in the 2016 series and Beastars.

She published the first stories of Beast Complex in Weekly Shonen Champion throughout 2016.

[13] Itagaki made Beastars in response to her editor asking for a longer and more sustainable story.