The Dark portal were ancient teleportation devices created by the the mysterious Xen many years ago. It allowed them to travel through time and space. Some who traveled great distances through the portal and exposed to its energy were permanently altered in appearance. After a war with the evil Dark King and his followers, the Xen were wiped out to extinction.
Although the Xen were gone, their portals had been left behind scattered throughout the universe. Those on Earth soon fell into the hands of terrorists and other criminals. The terrorist organization Dark Origin and its leader Johnson possessed at least one which was used to transport them to the Colony. However, it later malfunctioned and was destroyed shortly after the battle of New York.
By 2035, one Dark portal was known to still exist in Hill Nothing. It was quickly under the control of Johnson and his new Company. It would later transport himself and Colonel Damus to Hell. Following Johnson's defeat it was unknown what happened to the last Dark Portal.