1) Smaug (The Hobbit)
It won’t be teaching him any lessons in humility, but there’s only place for one of the most boastful, arrogant, and powerful dragons in known fiction: #1! Smaug is like a nuclear bomb with wings, decimating any city or town to nothing but ash and forcefully evicting dwarves. And its only fitting that his one weak spot be obnoxiously small and in an inconvenient location. No pressure, Bard. No pressure.