The Beast Within: A Gabriel Knight Mystery (also known as Gabriel Knight 2: The Beast Within) is an interactive movie point-and-click adventure game, developed and published by Sierra On-Line for MS-DOS, Macintosh, and Microsoft Windows, and released in 1995. The live-action scenes star the talents of Dean Erickson and Joanne Takahashi in the game's lead roles. The sequel to 1993's Gabriel Knight: Sins of the Fathers and the second entry in the Gabriel Knight series, the game 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 involved in a new case within Germany that focuses around a werewolf that has begun killing people around the city of Munich, and has connections to the lives of two famous people of Germany's history.

Unlike its predecessor, the game was produced entirely in full-motion video – a technology that was popular at the time for game production but expensive to use. The game's story not only incorporates the mythology of werewolves and the rich history of Bavaria in its plot, but also improved on gameplay, including the involvement of a second playable character for exploration of the story in their perspective. Production on the game included recasting the roles of the main characters, due to the actors that voiced them in the previous title being unsuitable to portray them, and using computer-generated scenery for the location in the game, with filming minimized to two takes, and voice-over recording constrained to a single day due to the production budget.

The Beast Within garnered critical praise for its storytelling and characterization, and has made appearances in numerous "best" lists, but was not a commercial success following its release. Despite this, it spawned a sequel, Gabriel Knight 3: Blood of the Sacred, Blood of the Damned, in 1999.