In Greek mythology, Xanthus ("yellow"; also Xanthos) is the name of several individuals and creatures.

• Xanthus is the name of one of Achilles' horses; see Balius and Xanthos.
• Xanthus is one of the Mares of Diomedes.
• Xanthus is a son of Phaenops who was killed by Diomedes.
• Xanthus is the name of one of Hector's horses.
• Xanthus is the gods' name for Scamander.
• Xanthus was a Theban king, the son of Ptolemy. He was killed by Andropompus or Melanthus.
• Xanthus was the son of Erymanthus and father of Psophis.
• Xanthus was a son of Pan who was allied with Dionysus.
• Xanthus was the lover of Alcinoe, who left her family to be with him.
• Xanthus was a king of Termera.
• Xanthus was a son of Aegyptus; he married Arcadia, one of the Danaids.

Xanthus was the name of an ancient Lycian city, beseiged by the Persians circa 546 BC, and by the Romans circa 42 BC.

Xanthus is the name of Aristotle Bolt's estate in the 1975 Disney movie Escape to Witch Mountain.