The OIA is the Outerworld Investigation Agency meant to control the multiple realms throughout Cambonnius. It currently contains Major Jax Briggs, Lieutenant Sonya Blade and the cyborg Cyrax

The OIA operations are focused on the Mortal Kombat tournament which allows representatives to invade other realms with successfull warrior victories. Because of this each OIA member must be able to participate in the tournament. Besides keeping track of the Mortal Kombat tournament the OIA also keeps track of it's former competitors and their affiliates such as Goro of the Shokan race and Shao Khan, the current emperor of Outworld.

The group is also rumored to be in contact with some mortal gods who are meant to be guarding Cambonnius from internal realm conflict.