Duke Thomas is the daytime protector of Gotham City, and his metahuman light sensory powers make him unlike any of Batman's other crimefighting partners.

While Batman and most of his allies operate at night, crime in Gotham City is quite different in the daytime, and so requires a different kind of crimefighter. Enter Duke Thomas—a.k.a. the Signal, the brightly colored agent of the Bat who hits the streets when the sun is out and Batman is asleep in his cave.

A being as old as the Multiverse itself, the Monitor watches the events of each Earth as they unfold from afar, outside the human concept of space and time.