Rincewind has one, believe it or not! Most of these are assist/indirect deaths,
with a lot of pushing people off high places or shoving them into the Luggage, because he hates to use weapons.
But he hates the risk of dying more, so he hasn't shied away from helping enemies meet untimely ends.
He hasn't had to kill anyone in MoM, but he also hasn't intervened when The Luggage has done its thing.
Oh, Rincewind did zap someone into dust with magic once in canon one, nearly forgot that one.
The Luggage could fill its own level of Hell with its creature/person kill count.
Sam has a more unfortunate list, with five kills (that I can remember). Three were technically in defense of others,
And include shifting from fly back to human while inside a vampire, shooting a man in the chest with a crossbow, and goring (and then crushing the heart of) Maryann the maenad
The other two were murder
One was the not-really-accidental-but-instantly-regretted-sorta-self-defense shooting of his first girlfriend Charlene,
and the second was the absolutely intentional shooting of her boyfriend. He hid those bodies and Just Doesn't Talk About It ever
Sam has yet to kill anyone in MoM, but he and Will came pretty damn close when busting up
the dog fighting ring, and he did kill AU!Will in the shared dreamscape
OH WAIT I LIED he helped Sylar kill an escaped convict who attacked him, but if I'm remembering right I think Sylar did the final deed
he did. LIKE A GOOD PERSON.
body of said convict is still buried in the woods behind Sam's cabin
jorah should dig that up some time