Gabriel Knight 3: Blood of the Sacred, Blood of the Damned is a point-and-click adventure game, developed and published by Sierra Studios for Microsoft Windows, and released in 1999. The sequel to 1995's The Beast Within: A Gabriel Knight Mystery and the third title in the Gabriel Knight series, the game's story focuses on the lives of Gabriel Knight, an author who is descended from a family that combats supernatural evils, and Grace Nakimura, a student who assists Gabriel, as they become engaged in a case that involves tracking down a kidnapped infant by vampires that is connected to the Holy Grail and Jesus. The setting is based on a real-life conspiracy theory about a hidden treasure, and involves elements of history and myths surrounding the Grail, vampires, and the Knights Templar.

Unlike previous installments, the game was fully rendered in 3D with a far greater level of puzzle solving and exploration, and featured a score that expanded upon some of the piece used in previous titles. Due to a return to animated scenes, Tim Curry returned to reprise his role as the voice actor for Gabriel; the character of Grace was recast a second time. The game was the last to be published by Sierra in the wake of the crash of the adventure video game industry, but was not a commercial success as its predecessors. It however managed to receive mainly positive reviews from critics, with two of its puzzles receiving polarising feedback on their construction – one for being frustrating, the other for being well crafted.

The game was released as part of Sierra's Best Seller Series in 2001, and re-released for GOG.com in 2010, and Steam in 2016.