"I won't let my comrades die" - said by Kakashi Hatake from Naruto.

These brave heroes and heroines protect things from known or unknown threats whether it's foregin or domestic. Often times, they are led by a conviction to protect what is important is often a motivation to push these people into fighting against villainy such as protecting loved ones or comrades. All in all they are guardians who will protect what is important to them no matter the cost.