She killed her crew and 4 hundred vidiians in Deadlock.
She killed hundreds of thousands of Swarmies in Swarm.
She Killed a Clown in the Thaw.
She hurt herself really badly in Futures End to kill Dunbar.
Everytime she fired that seemingly independencry war pistol to defend bleeding out Q during his rebellion... A star blew up. It's possible the Q only put Stars in the chamber that didn't have life supporting planets in the orbit of... But do you think they really care that much?
She forced the Queen to murder hundreds of thousands of Drones in Unimatrix Zero because Kathryn broke to Borg Interrogation from being capable of 200 thousand drones rathert han 100 thousand drones... A matter of seconds.
She invented WMDs to slaughter Species 8472... She took out one ship to make an example weighed in blood (what passes for blood.) to bully a universe into being terrorified of her.
She killed B'Elanna multiple times in Barge of the Dead
Nuvok from Riddles was ordered to kill himself no matter how much he believed that he was a real person, just like she ordered Tuvix to top himself before him.
In Fury, Season One Janeway shot (old) Kes dead with a hand phaser and time was not reset, and her corpse was in Voyagers hold for 6 years... Possibly seven but they just stopped talking about it.