What Shall We Do with a Jedi Mentor Earl-aye in the Morning?by Dave Butler
Continuing in the vein of thinking about plot and characters overcoming obstacles, let's talk about mentors. A mentor can be a great thing in your story -- he (Obi-Wan, Dumbledore, Phineas Pimiscule, Gandalf) allows you to start your protagonist (Luke, Harry, Sky Weathers, Bilbo / Frodo) out as an outsider, like the reader, and then get transitioned into your fantastic setting (the galaxy outside Tatooine including the ways of the Force, Hogwarts and the wizarding world, the skills and lore of monster hunters, Middle Earth outside the Shire). His superiority to your main character shows the room the main character still has to grow. The mentor gets your protagonist over the threshold from the ordinary world and into the adventure, pointing the way and setting an example.
But the superior prowess of the mentor poses a problem, which should now be immediately obvious. As long as the mentor's around, the protagonist isn't really in any trouble. Obi-Wan will fight off the Mos Eisley thugs, Gandalf won't let the trolls or the wargs get Bilbo, and if Dumbledore doesn't intervene in person, he can be counted on to send a phoenix with a sword inside a magical hat. So if your mentor sticks around, he becomes a deus ex machina, he converts your protagonist into a damsel in distress.
So squeeze your mentor for all the goodness you can get out of him, and then get him out of the way. Send him off on dark journeys alone (Gandalf), have him held hostage so that the hero can rescue him (Phineas) or, yes, just plain kill him (Obi-Wan and Dumbledore, Qui Gon Jinn, et cetera, et cetera).