The Phantom
"YOU SHALL NOT PASS!!!!!!!" - the Phantom
When Phantom 's body was destroyed, his spirit wandered the Multi-Universe until it entered Johnathan Tangelo , where he remained in a deep sleep until Unicron 's curse it brought back from the brink of oblivion. Though the potential for this warrior was great, it's power was hindered by the constant conflict between Johnathan and Phantom.
Both sides constantly fought for control of the body. But there was one thing that they agreed on: they needed to find a way to separate from each other. It was at this point that Phantom yielded his control of the body to John, who then formed the HailFire Empire and eventually managed to get Angemon and Angewomon to release him by taking the Trials of the Heart, Soul, and Mind.
As the battle between them and Unicron grew closer, Phantom became impatient, seizing control of the body and acting of his own accord. He had a conversation with Cad Bane, Mystique, and Deadpool in the middle of outer space in front of a sun. Enraged by one of Deadpool's comments, he threw the mercenary into the sun and watched as he burned and healed over and over again. John managed to regain control long enough to get Deadpool out of the sun, but lost control to Phantom once more.
In their final stand against Unicron, they sacrificed themselves to not only save the others, but to separate from each other. Their last words before sacrificing themselves were, "YOU SHALL NOT PASS!!!!!!!"
Though they were separated at last, only Phantom immediately regained a physical form. John was revived later using the Dragon Balls on Cybertron.