Forgotten One (Lords of Shadow)

"You cannot triumph here, fool! You have no comprehension of what you are up against!"

- The Forgotten One to Gabriel

The Forgotten One is the main antagonist and final boss in Castlevania: Lords of Shadow's two DLC stories, Reverie and Resurrection.

Game Description
The Bernhard family were responsible for a vast number of hideous crimes, most of them involving foul sorceries and demonic rituals; the most horrible of them all was the summoning of the creature known as "The Forgotten One", an evil monster of immense power. This entity was the sovereign of the elemental Plane of Darkness, and quickly escaped the Bernhards' controlling magic. Finally, the three founders of the Brotherhood of Light fought the demon and used their powers to imprison it forever... or so they thought. Today, the monster impatiently awaits the time of its release, eager to seek retribution against all humanity...

Story
After Gabriel Belmont defeated Satan and the Lords of Shadow, he declared his victory hollow after his wife Marie ascended to Heaven, and his humanity was broken. He was summoned to Carmilla's castle by Laura to be informed that after defeating the Lords of Shadow, he has unleashed a greater evil in the world. Defeating them weakened the seal that imprisoned the Forgotten One established by the founders of the Brotherhood of Light. As soon as he's freed, the Forgotten One will lay siege to the world, killing everyone. At first Gabriel refused until Laura convinced him not to have the blood of the innocent on his conscience. Once they reached the portal to the dimensional prison, Gabriel couldn't go in, because humans will die in the dark world. At the request of Laura to free her of her miserable existence, Gabriel drank all of her blood, becoming a vampire and killing Laura.

Encountering the Forgotten One in the prison, Gabriel started attacking him while part of the Forgotten One's power is destroying the first seal. Claiming that his power is limitless, the Forgotten One and Gabriel battled with Gabriel taking out pieces of his armor and attacking the exposed parts, starting with the knee and then the torso. The Forgotten One admits that he had underestimated Gabriel and that he is a worthy opponent, but still claims that he is no match for him. After reclaiming his power from destroying the first seal, Gabriel hid while the Forgotten One declared that he will never find peace in light nor darkness.

After the Forgotten One shot off part of his power to destroy the second seal, Gabriel attacked once again, exposing the Forgotten One's hand with the dark gauntlet. He took out more pieces of his armor, exposing the shoulder and the head. After a lengthy battle, the second seal was destroyed. The Forgotten One was confident that Gabriel had failed and said that all the pain inflicted on him by the Brotherhood of Light, he is going to inflict on the world ten fold. He decided to let Gabriel live so he can witness his failure, which proved to be his biggest mistake. Before the Forgotten One could reclaim his power from the seal, Gabriel jumped in front of the Forgotten One, and he absorbed the power instead. Knowing that he was outmatched, the Forgotten One surrendered and pleaded mercy, but Gabriel killed him with a swipe of lightning. This was the beginning of Gabriel Belmont becoming the Lords of Shadow incarnation of Dracula.

Trivia

 * The Forgotten One is voiced by Colin MacFarlane.
 * There is also an evil creation in the original Castlevania timeline called the Forgotten One.