Cu'um

Cu'um is a mentioned character in Elden Ring.

Location
Cu'um's whereabouts are currently unknown, however there are many pointers in Cu'um's Castle and dialogue spread about by Gawr Gura, Simp Rupert and items, weapons and key items scattered across his castle. The most common theory that almost every clue given is that he made an invention that caused molecules to burn up and scatter to a different location, and in this scenario, the cosmos. It is possible that Cu'um had also died from lack of oxygen even though his followers still look up in the sky and claim to see his sorrowed soul drifting endlessly with no intention.

Lore
He is mentioned to have been the creator of Cu'um's Castle, as well as a scientist and inventor. There are also inicators that he was not the original founder and his ancestors were possible makers of the castle but met a grim fate as the foundation slowly collapsed due to a build up of rust and the nation's land drying out.

Referred to as "a pretty sticky guy" by Gawr Gura.