The manga had a bit more death than the anime, but that could be because there were a few more characters and the events were different.
Sailor Galaxia
Mamoru
He was killed during act 43 right after he purposed to Usagi. Galaxia appeared behind him and tore out his Sailor Crystal, sending the moon soldier into shock.
Sailor Pluto, Sailor Saturn, Sailor Uranus, Sailor Neptune
Pluto, Uranus and Neptune originally traveled to their respective castles because of the threat which was reaching Earth. Saturn originally stayed behind but then followed Pluto. They all technically get killed by Galaxia in act 45, but we do not see their deaths until sometime later and it is only in brief images.
Sailor Mars, Sailor Venus
Sailor Mars originally sensed something was wrong at the temple and got there in time to see Phobos and Deimos being killed by Lead Crow. Venus showed up a short time later and fought the Sailor Animamate. Things were looking down, but soon Sailor Moon showed up and put an end to the troublesome foe, but before the friends could be reunited Galaxia showed up and put and end to that. They were killed in Act 45.
Sailor Tin Nyanko
She was also killed for her failure just like in the anime only she never turned partly good. She fled after Sailor Star Healer showed up during her attack on Luna and Artemis. She made the mistake of returning to the Galactica Castle. Galaxia was not happy at all and in a single move, took away her bracelets. She died in Act 47.
Evil Mamoru
Yes, Mamoru was brought back from the dead (under Galaxia's control of course) only to be used a torment item to mess with Usagi's mind. In act 51 he was knocked off into the Galaxy Cauldron right before Sailormoon's eyes.
Sailor Chibimoon
She was also killed in Act 51, but indirectly by Galaxia. After Mamoru was killed for a second time, Chibimoon faded away into nothing.
Sailor Aluminum Seiren
Sailor Jupiter, Sailor Mercury
They both died in Act 44 at the same time. First they were caught in Seiren's hair (yes, she can use her hair as a weapon) and then lost their Sailor Crystals to her.
Sailor Lead Crow
Phobos, Deimos
Phobos and Deimos are both from the same planet Lead Crow comes from, Coronis. They were killed by her while trying to fight back during Act 45.
Sailor Lethe
Luna, Artemis, Diana
The three cats met their end in Act 48 when Sailormoon was under the spell of the River of Oblivion. They had already been injured by Tin Nyanko earlier and couldn't really do anything, and it is uncertain how they got there in the first place.
Sailor Phi
Sailor Lethe, Sailor Mnemosyne
Both were killed at the same time in Act 48 for becoming a "traitor" to the Shadow Galactica empire. Mnemosyne didn't want to hurt a fellow Sailor Soldier and Lethe finally agreed and let them pass through their rivers.
Sailor Chi
Sailor Star Fighter, Sailor Star Healer, Sailor Star Maker
In Act 48 right after Sailor Phi had killed Lethe and Mnemosyne, Sailor Chi put an end to the Sailor Starlights. They were still unconscious and could do nothing about the attack.
Sailor Kakyuu
She meets her end right after Sailormoon kills Sailor Phi. She is stabbed right in the back with Chi's staff. She's killed in Act 49.
Chaos
Galaxia
Galaxia starts to turn good after she is betrayed by Chaos and almost knocked into the Galaxy Cauldron, but is saved by Sailormoon. Still, she meets her end in Act 51 when her bracelets are shattered.