Bigfoot killing the poacher to protect the park ranger.
Speaking of primate cryptids, the Devil Monkeys managing to overpower and kill three armed police officers very easily. Given this is a series where most creatures (with the possible exception of Q) lack bullet immunity, that is pretty awesome.
The dad of the family in "Vampire"stabbing an attacking vampire to death to protect his family.
And what does he use to achieve this? A wooden stake, of course!