Salentin VIII of Isenburg-Grenzau (German: Salentin VIII von Isenburg-Grenzau) (c. 1532 - 1619) was the Count of Isenburg-Grenzau from 1610 until 1619. Salentin was the eldest son of Count Salentin VII and Antonia Wihelmina of Aremberg. He succeeded his father in 1610, and after his death in 1619 was succeeded by his younger brother Ernest.