Emerald Weapon (Final Fantasy VII)
Mike Tyson (Punch-Out)
Death (Castlevania 1)
Yellow Devil (Mega Man)
Although honestly I think Ruby is harder than Emerald... BUT maybe Emerald is more memorable due to it sneaking up on you, and due to the timer, and therefore more deserving of a rushmore seat.
People who don't finish their sentences
I'm a Castlevania superfan! Ask me anything!