The Serene Wanderer is a mysterious entity with the appearance of a chalk-white floating woman, wearing a dark blue cape, and with a star-like symbol on her chest. She claims to have a million names, and seems to know much about the interdimensional locality called the Nexus. She also was quite in the picture regarding Eustace Boyce's new assignment (to Hell) when his soul arrived in the Nexus, and made sure that he arrived there.
The Serene Wanderer was also present when the Sheriff had to repair the Great Membrane after it was pierced by the Cosmic Shelf. She could be seen helping him doing this task, together with the Architekt.