noun
Literary or formal term for someone who has died; often used in historical or dramatic contexts.
彼は既に亡き者となっていた。
He had already become a dead person.
亡き者の名を呼ぶのはやめてくれ。
Stop calling the name of the deceased.
Compound of 亡き (archaic adnominal form of 亡い, 'dead') + 者 ('person'). The spelling 無き者 uses 無 ('nothing') to emphasize absence.