Clytius (, also spelled Klythios, Klytios, Clytios, and Klytius) is the name of multiple people in Greek mythology:

1. A son of Laomedon, brother of Priam, and an elder of Troy. By Laothoe, he was the father of Caletor, Procleia and Pronoe or Pronome, of whom the latter was the mother of Polydamas by Panthous.
2. A young soldier in the army of Turnus who was loved by Cydon in Virgil's Aeneid, and was killed by Aeneas.
3. One one of the Giants, sons of Gaia, killed by Hecate during the Gigantomachy, the battle of the Giants versus the Olympian gods.
4. An attendant of Telemachus in Homer's Odyssey, the father of Telemachus' friend Peiraeus. Dolops, a Greek warrior killed by Hector in the Iliad, could also have been his son.
5. One of the sons of Aeolus who followed Aeneas to Italy and was killed by Turnus.
6. Father of Acmon and Menestheus from Lyrnessus, Phrygia.
7. Father of Euneus (one of those killed in the battle between Aeneas and Turnus).
8. An Argonaut, son of Eurytus of Oechalia and Antiope, brother of Iphitos. According to Hyginus, he was killed by Aeetes, if indeed the text is not corrupt; according to Diodorus Siculus, however, he was killed by Heracles during the latter's war against Eurytus.
9. A son of Alcmaeon and Arsinoe/Alphesiboea. He moved from Psophis to Elis in order to escape his mother's vengeful brothers. The Clytidae, a clan of soothsayers, claimed descent from him. According to Stephanus of Byzantium, his mother was Triphyle, the eponym of Triphylia.
10. An Athenian, father of Pheno who married Lamedon. Ianiscus, descendant of this Clytius, became king in Sicyon after Adrastus.
11. Each of the three namesakes among the suitors of Penelope: one from Dulichium, another from Same, and the third from Zacynthus.
12. A man killed by Perseus in the battle against Phineus.
13. A warrior in the army of Dionysus during the god's Indian campaign. He was killed by Corymbasus.
14. Son of Agriopas and grandson of Cyclops. He fought in the war between Eumolpus and Eleusis and fell alongside Eumolpus' son Immaradus and Egremus, son of Eurynomus.
15. In a rare version of the myth, a son of Phineus and brother of Polymedes: the two brothers killed Phineus' second, Phrygian, wife (Idaea?) at the instigation of Cleopatra.
16. An alternate name for Clytoneus, the son of Naubolus of Argos and father of Nauplius II.