Literary or formal term for someone who has died; often used in historical or dramatic contexts.
He had already become a dead person.
Stop calling the name of the deceased.
死人 is a blunt, factual term for 'dead person'; 亡き者 is more euphemistic and poetic.
Standard kanji spelling for 'dead person'.
Alternate spelling using 無 (nothingness), less common.
Compound of 亡き (archaic adnominal form of 亡い, 'dead') + 者 ('person'). The spelling 無き者 uses 無 ('nothing') to emphasize absence.