The Pageant was a group of other-dimensional beings who wore masks to give themselves identity and could alter reality through their machinery.
Curious about Earth history and philosophy, they took it out of the main universe around 1794. They made alterations to it and placed it in another dimension to see what would happen. They did not intend to cause harm to the human race, but the experiment got out of hand. Once brought under control, they restored the Earth to its original location in space and time and promised not to perform any similar experiments. The project's leader and Masksmaster was Robin Goodfellow. (PROSE: The Man in the Velvet Mask)
Along with Faction Paradox and the Ministers of Grace, Masksmakers of the Pageant went back in time to help the effort against the Mad Mind of Bophemeral in the Millennium War. (PROSE: The Quantum Archangel)