Belthasar

Belthasar is the Guru of Reason from Chrono Trigger.

Break the Seal!
When Crono's party opens the sealed doors in Keeper's Dome using the pendant, the Nu reveals himself to be the remains of Belthasar. He then explains his past and the Epoch to them.

He once lived in the Kingdom of Zeal in 12,000 B.C., but an accident threw him through time and into 2300 A.D. He also explains that the entity called Lavos is constantly consuming the energy from the planet, slowly killing it and all living things on it.

Because he was growing old and frail, he downloaded his memory into the Nu. He then allows Crono and his friends access to his final invention, what he calls the "Wings of Time", the Epoch.