The Librarian

they are an entity that can travel through dimensions by using a pocket dimension that exists in areas with little to no light, or just shadows. It does not have a name but most other entities know it as The Librarian because It collects and stores knowledge from all the different worlds it's been to. most people cannot see it almost as though it doesn't exist, besides entities and other supernatural creatures, but for some reason unbeknownst to it, you can.