The Mentor

The one who taught Hero everything they know. They're usually much older than Hero. They also teach The Audience about the background of the world, such as critical historic events, how the world works, and why certain things are what the are.

For some odd reason, Mentor has a thing for dying. They're rarely ever around to see Hero win The Big Fight against Villain, but they might die once the time for final conflict is near. In certain cases, Mentor will help out in The Big Fight, but might also die in the process.

Anime

 * Naruto: Kakashi Hatake and Jiraya - Both serve as Naruto's mentor. Kakashi came first and taught him most of the basics of the ninja world, then Jiraya taught Naruto how to use his most important technique: Rasengan.