The relationship between what is considered canon and non-canon in popular horror and sci-fi movie and TV franchises has always been a curious one, in my opinion. Usually, only the movies and/or TV episodes are considered canon, while other stories that take place in the same franchise but are told in video games and print (such as novels and comic books) are not. Yet this is not to say that the non-canonical elements in a franchise have no influence at all on what is later considered canon. For example, several story ideas that first appeared in Predator and Terminator comic books eventually re-appeared in each of the Predator and Terminator movie sequels (and, in the case of Terminator, in The Sarah Connor Chronicles TV series). Another example of the relationship between canon and non-canon happened in the recent fourth season finale in the Star Wars: The Clone Wars, when Darth Maul returned to take his revenge against the Jedi order.
Darth Maul in Star Wars: The Clone Wars.
The return of Darth Maul was originally suggested in a short story that appeared in Star Wars: Visionaries, a one-shot comic book that was published by Dark Horse Comics shortly before the release of Revenge of the Sith back in 2005. To further verify the connection between comic book and cartoon, the Force-powered cyborg Maul in Clone Wars looks almost exactly like the Force-powered cyborg Maul in Visionaries.
Darth Maul in Star Wars: Visionaries.
Fortunately, resurrecting Maul is more than just a ratings stunt for Clone Wars. The two-part finale that depicted the return of Maul was a fantastic way to wrap up an already outstanding season of this series, and it laid the roots for the Maul's ongoing menace during the fifth season. I'm assuming that Maul will continue his revenge against the Jedi, and perhaps even cause some trouble for Count Dooku (a.k.a. Darth Tyranus), the Sith apprentice who took his place. Also worthy of note is that Maul is voiced by veteran Star Wars voice actor Sam Witwer, who previously contributed his talents to The Force Unleashed video games and the Planet Mortis story arc during the third season of Clone Wars. Check out Witwer practicing his craft in the recording booth along with Clancy Brown (who voices Maul's brother, Savage Opress) in the video clip below.