The Great One's true form is an immense brain, perhaps a half mile in diameter. Within his mindscape he projects a mental construct of himself, using a form matching that of each race he visits, though somewhat larger in stature.
His origins are unknown, the Great One roamed the universe, seeking out endangered planets and offered them protection by converting both planet and population into brainwaves retained into his mind; hundreds of planets' populations elected to exist within the safety of his mind. In recent years, the Great One made this offer to the Zenn-Lavians, whom he saw as honorable people caught between the waring Kree and Skrulls. Feeling they could not count on the Silver Surfer's protection forever, the Zenn-Lavians unanimously accepted. as they left the physical plane, empress Shalla-Bal sent a parting psychic message to her lover Norrin Radd, the Silver Surfer. Recieving what seemed to be a distress call, the Silver Surfer flew to the rescue and discovered his former world missing. The telepath Moondragon sensed the Great One's presence and revealed him to the Silver Surfer, who had Moondragon transport his astral self into the Great One's psychic plane. The surfer found Shalla-Bal and the others at peace with their existence, and he learned that in this realm he could resume his mortal form as Norrin Radd at will, restoring his long-lost relationship with Shalla. Norrin chose to remain within the Great One's psychic plane, and for a blissful weeks he and Shalla enjoyed happiness as never before.