Best Yandere Character? Gunter -- Kyo Kara Moah
Your Majesty, I love you!
So a Yandere character is generally considered a little more violent than I would categorize Gunter to be. The long haired bishounen is definitely a little crazy about Yuri, the Demon King, but I don't think he would hurt anyone in pursuit of his obsession.
I just kind of like how his reality is so different than every other person's because it is so colored by his idealized vision of Yuri.