>>542389309
>I know Katya would likely be no. 1 since she was a mercenary
Tess probably has a higher killcount, though it's up for debate if Yehrussians are people.
Acacia's backstory is covered in black ink, but we know she was a spec ops girl that used knives. I doubt her enemies lived.
Katya meanwhile uses a crossbow as a merc. She can totally just leg-shot someone and leave them alive.