Being a movie mentor comes with certain expectations. You've got to be wise and strong, capable of imparting great wisdom while still giving off the impression that you could whup most people if they so much as annoyed you.
Movie mentors should exude a certain authority they've been there and done it before, and it's now their job to train up the protagonist. Occasionally, the movie mentor turns out to be the villain. If the film's really being clever, it's made clear the mentor is the villain throughout. But regardless of their status within the narrative arc, the movie mentor must always prove him or herself to be competent in their position. Because if they're not, then what's the point?
Yet it must be noted that there are plenty of pitfalls for a potential mentor. Sometimes their methods are just bafflingly wrong, other times they can do the job better themselves and occasionally they just haven't thought everything through properly. It's extremely easy to fall down in this role, and any mistakes become all the more embarrassing because they're supposed to be the wisest person in the room. It's these people this article is about - the mentors who will live on in infamy thanks to their own idiotic decisions. Keep in mind, a SPOILER WARNING is in effect.