The Bloody Sun is a science fantasy novel by American writer Marion Zimmer Bradley, part of her Darkover series.

The novel was substantially rewritten, expanded, and republished under the same title in 1979; Bradley's short story "To Keep the Oath" was included in this edition and all subsequent reprintings.

The expanded rewrite retains the basic plot structure but is more closely connected to several other Darkover books, especially The Forbidden Tower.

It also changes the identity of one of Kerwin's parents, although the later book Exile's Song uses his textually original parentage as background information.

He also realises that Auster and Ragan are twins, the true children of Jefferson Kerwin, by Cassilda Lanart-Ridenow.

The couple seeks help from Dyan Ardais, Elorie's half brother, to obtain an audience with Lord Hastur.

Hastur admits that he should have done more to protect Cleindori, and her father, Damon Ridenow, saying he will not make the same mistake with Elorie.

Jeff tells the circle that the experience proves Cleindori was right – that matrix mechanics are a science, not a mystical art, and that a keeper need not be a cloistered virgin.