The Uni-Power is an extra-dimensional force that possesses an individual (or on one occasion, twins) in a time of crisis, transforming that person into Captain Universe. As Captain Universe, the transformed person typically retains his or her original personality and appearance, though with Captain Universe's costume and heroic traits superimposed over the original. The Uni-Power itself emanates from the Enigma Force, the exact nature of which, naturally, remains an enigma. It is believed, however, to be connected to the Microverse, home of the Micronauts. Although the Uni-Power typically empowers normal, non-super-powered humans, it has in the past empowered Doctor Strange, Spider-Man, Commander Arcturus Rann of the Micronauts, a toddler, and a dog, among others. Its counterparts in various alternate timelines have also possessed Mar-Vell, Mr. Fantastic, a member of the alien Badoon race, a Doombot and Quasar. Because of its never-ending supply of energy it has been the target of many individuals, terrorist groups and peacekeeping agencies such as AIM, the Psycho-Man, Doctor Doom and even S.H.I.E.L.D.