Ragnarök

Ragnarök is a term initially uttered by the Emperor of Britannia when Lelouch forms his Geass contract with C.C.. With the use of the Sword of Akasha, the Thought Elevator, and two Codes, the Emperor can force the collective subconscious of human beings onto the surface of their mask and affect reality, making all humans, both living and dead, into one being. For this reason, the Emperor connected every thought elevator on the planet. He then intended to unleash Ragnarök using the thought elevator in Kamine Island. This contract was made between Charles zi Britannia, Marianne vi Britannia, C.C. and V.V., where they would destroy the gods and unite all humans, living and dead into one being. This plan was thwarted by Lelouch vi Britannia when he used his Geass to compel the gods to keep existing and to keep time moving. This resulted in the death of both of his parents.

Trivia

 * The concept of Ragnarök is very similar to the Instrumentality of Neon Genesis Evangelion, both in the idea and the way it is carried out, a plan where a secret cabal of the worlds' elite and powerful work to unite all of humanity into a single entity with the purpose of saving it. The major difference is that Ragnorak ultimately failed, while the Human Instrumentality Project was successful.
 * It is also very similar to Project Tsuki no Me from Naruto, however this is only in concept, as the two were carried out in very different manners.