Isis is the ancient Egyptian deity who travelled furthest. In the Hellenistic and Roman periods her cult spread out of Egypt across the entire Mediterranean, carried by traders and soldiers; temples to her stood at Pompeii, in Rome, and as far as Roman Britain. Recast as a universal goddess who answered personal prayer and offered her initiates a hope beyond death, she became one of the leading mystery religions of the Roman Empire. Apuleius, in The Golden Ass, gives a famous first-person account of an initiate for whom Isis is the single goddess behind all others' names.
Scholars have long noted, carefully, the resemblance between images of Isis nursing the infant Horus (Isis lactans) and later Christian images of the Madonna and Child, and between aspects of her devotion and later Marian piety. The relationship is debated and should not be overstated into simple derivation, but the visual and devotional continuities across late antiquity are real and much studied.
Her worship in Egypt itself outlasted almost everything around it: the temple of Isis at Philae, in the far south, remained active into the sixth century CE, among the last functioning temples of the old Egyptian religion.