The one and only True Death, The reaper of Teyvat that works unrelated to Celestia, The Heavenly principles trying to hunt down the Traveler, Aether. To him, Aethers time should've stopped ticking in Sumeru but he gave Aether more time out of curiosity and watched what happened. But its been enough. Its time, for The Death to take matter into his own hand if Aether is not gonna be dying via Natural causes soon.