The Amber Chronicles
created by Roger Zelazny
The Chronicles of Amber is group of novels that comprise a fantasy series written by Roger Zelazny. The main series consists of two story arcs, each five novels in length. Additionally, there are a number of Amber short stories and other works.
The Amber stories take place in two, true worlds: Amber, and the Courts of Chaos. Other worlds, including our Earth, are but "shadows" of the tension between the two true worlds. The Courts of Chaos is situated in Shadow at the very edge of Chaos itself. Royals of Amber who have negotiated the Pattern, can travel freely through the shadows. By shifting between shadows, one can appear to alter reality by choosing which elements of which shadows to keep, and which to move between.