Pluto dies in the Black Moon arc after using the Time Stop.
Mercury and Jupiter die in SailorStars.
Venus and Mars are killed by Galaxia in SailorStars.
Outer Senshi die in SailorStars.
Mamoru dies in SailorStars.
Evil Sailor Senshi are killed by Eternal Sailormoon.
Probably one of the saddest deaths I've ever seen in the manga. Lethe and
Mnemosyne die touching each other's hands like Neptune and Uranus death
in the anime.