RWBY - The real crime is Salem robbed us of Queen and Archer Waifu

A couple of background characters that didn't survive the God of Darkness' snappening.

Considering how they spoke of things before they left, it can be inferred that Remnant was the ONLY planet with life in that universe at the time. So in a sense it would be the same as killing every sentient life in the universe.
Though they didn't kill the animals, which were also included in the half Thanos took, so he still has a proportionally bigger amount of death than the Gods.
And even then, Galeem from Smash Ultimate has both of them beat, killing all life in the vast Smashverse except Kirby.