Dormammu

Dormammu, along with his sister Umar, is a mutant member of an extra-dimensional society of energy beings called the Faltine. Unlike other Faltinians they were not perfect copies of their progenitor Sinifer given some unknown mutation and they hungered for matter instead of energy. They were banished from their home dimension for turning Sinifer into matter, which was considered the equivalent of murder. The siblings eventually discovered the Dark Dimension and insinuated themselves into the role of advisors to King Olnar. In exchange for power and protection, Dormammu and Umar taught Olnar how to exploit the natural pocket warps of the Dark Dimension and absorb other dimensions/universes into it. When Olnar died in an attempt to conquer the realm of the Mindless Ones, the siblings used the opportunity to murder most of the Mhuruuks (the magical priest class under Olnar’s rule) and successfully sealed off the Mindless Ones from the rest of the populace. They secured rulership of the realm under the guise of heroes for ages. Later on Dormammu would banish Umar after the same had given birth to Clea into one of the pocket dimensions under his control, taking sole custody of the Dark Dimension.