battle casualty; combat casualty
Refers to a person killed, wounded, or missing in combat. A formal, somewhat technical term used in military or news contexts.
There were many battle casualties in that fight.
A general term for 'victim' or 'casualty' in any context (accident, disaster, etc.), while 戦闘犠牲者 specifically means casualties from combat.
Compound of 戦闘 (sentō, 'battle') + 犠牲者 (giseisha, 'victim, casualty').