Which dog is the main villain in the 2002 live-action film?

The main villain in the 2002 live-action film is Scrappy-Doo.

In the film, Scrappy is revealed as the mastermind behind the supernatural events at Spooky Island. He has transformed into a large monster called Scrappy Rex using the Daemon Ritus, a mystical device capable of changing souls and bodies. His plan is driven by resentment toward Mystery Inc., whom he believes abandoned him.

This twist deliberately reverses Scrappy-Doo’s traditional role. In the animated franchise, Scrappy is Scooby’s energetic nephew and is usually an enthusiastic, troublemaking ally. The live-action movie instead turns him into the central antagonist, while other apparent villains—including Emile Mondavarious—are connected to the larger scheme.

The 2002 film was directed by Raja Gosnell and written by James Gunn. Scrappy’s villainous reveal became one of the movie’s most discussed choices, partly because Gunn had disliked the character and partly because younger fans had strong affection for Scrappy. The film was released on June 14, 2002, and was followed by “Scooby-Doo 2: Monsters Unleashed” in 2004.