Bellerophon or Bellerophontes (Ancient Greek: Βελλεροφῶν; Βελλεροφόντης; lit. "slayer of Belleros") or Hipponous (Ancient Greek: Ἱππόνοος; lit. "horse-knower"), was a divine Corinthian hero of Greek mythology, the son of Poseidon and Eurynome, and the foster son of Glaukos. He was "the greatest hero and slayer of monsters, alongside Cadmus and Perseus, before the days of Heracles". Among his greatest feats was killing the Chimera of the Iliad, a monster that Homer depicted with a lion's head, a goat's body, and a serpent's tail: "her breath came out in terrible blasts of burning flame."

Bellerophon was also known for capturing and taming the winged horse Pegasus with the help of Athena's charmed bridle, and earning the disfavour of the gods after attempting to ride Pegasus to Mount Olympus.

One possible etymology that has been suggested is: Βελλεροφόντης (Bellerophóntēs) from Ancient Greek βέλεμνον (bélemnon), βελόνη (belóne) or βέλος (bélos, "projectile, dart, javelin, needle, arrow") and -φόντης (-phóntēs, "slayer") from φονεύω (phoneúō, "to slay").

However, Geoffrey Kirk says that "Βελλεροφόντης means 'slayer of Belleros'". According to the Scholia of Homer, Bellerophon was named so after having slain a Corinthian citizen of that same name by accident, while practicing his knife throwing, which caused him to be exiled to Lycia; this origin hypothesis would correspond to how Hermes got his epithet 'Argeiphontes' (lit. 'slayer of Argus') after slaying Argus. According to some scholars, Belleros could have also been a local Lycian daimon, as Bellerophon's name "invited all sorts of speculation".

The only other authors to mention a Belleros killed by Bellerophon are two Byzantine scholars, John Tzetzes and Eustathius of Thessalonica, who both seem to be following Bellerophon's own name-etymology.^{[AI-generated source?]}

Robert Graves suggests a possible etymology via beleēphoron, interpreted as "bearing darts". Joseph T. Shipley glosses the name Bellerophon as "slayer of monsters".

Bellerophon was the son of the mortal Eurynome (or Eurymede) and Poseidon; having been raised by his foster father Glaukos. He was the brother of Deliades (also named Peiren or Alcimenes).

Bellerophon was the father of Isander (Peisander), Hippolochus, and Laodamia (Deidamia or Hippodamia) by Philonoe,^{[AI-generated source?]} daughter of King Iobates of Lycia. Philonoe was also known under several other names: Alkimedousa or Cassandra, Anticleia, or Pasandra. In some accounts, Bellerophon also fathered Hydissos by Asteria, daughter of Hydeus.