Under a Blood Red Moon is an adventure module released in June 1993 by White Wolf Publishing for use with either of their tabletop role-playing games Vampire: The Masquerade and Werewolf: The Apocalypse, and is a part of the World of Darkness series.

The book was developed by Bill Bridges and Andrew Greenberg and written by Steven C. Brown, and is an early example of a cross-over between different role-playing games.

Under a Blood Red Moon is a cross-over adventure module intended to be used with the World of Darkness tabletop role-playing games Vampire: The Masquerade and Werewolf: The Apocalypse.

[7] It was among the first cross-overs between different role-playing games, preceded only by a few supplements such as TSR, Inc.'s Spelljammer (1989); writer Shannon Appelcline noted in his book Designers & Dragons that White Wolf Publishing was in a rare position in that all their games at the time were set in the same fictional universe, making cross-over books more feasible to produce.

[10] Appelcline did find one major problem with the adventure's gameplay, in that Vampire: The Masquerade and Werewolf: The Apocalypse work differently on a mechanical level, and do not go perfectly well together.

[1] Berin Kinsman reviewed Under a Blood Red Moon in White Wolf #38 (1993), rating it a 4 out of 5 and stated that "The big revelation here [...] is in the final appendix.