Worst character death?

What's the worst instance of killing off a character in all of Star Trek? Where was it done the worst?

I'm to go with >!Hugh's!< death in "Nepenthe" since it added nothing but cheap pathos, wasted a good supporting character, and shut down what had been a genuinely interesting storyline. Also because it was Narissa who did it, and she's honestly one of the most annoying villains ever.