The Architect
The Architect was the mysterious entity who oversaw the creation of the Strange and Wonderful House.
At some point, an individual gathered a group of creative people and showed them the as-yet-empty blueprints, infinite in size, for what would become the Strange and Wonderful House, and told them to put their imagination into creating as many distinctive, impossible rooms as possible. (PROSE: Our Strange and Wonderful House: Welcome!)
The Architect personally gave Jenny Everywhere a wing all to herself, which became the Jenny Everywhere Museum. (PROSE: Our Strange and Wonderful House: The Jenny Everywhere Museum)
Behind the scenes
Welcome! was written by Zxvasdf in his own name as the introduction to the Our Strange and Wonderful House writing challenge itself. However, metafictional elements in later entries which blurred the lines between the in-universe creators of the House and the real-life writers, as well as the cheekily partially in-universe tone of Welcome!, invite one to potentially consider it as a canonical part of the book's narrative. If so, its nameless first-person narrator is easily conflated with the figure of “the Architect”.