In Greek mythology, Enceladus (Ancient Greek: Ἐγκέλαδος, romanized: Enkélados) was one of the Giants, the offspring of Gaia (Earth) and Uranus (Sky). Enceladus was the traditional opponent of Athena during the Gigantomachy, the war between the Giants and the gods, and was said to be buried under Mount Etna in Sicily.

Enceladus was one of the Giants, who (according to Hesiod) were the offspring of Gaia, born from the blood that fell when Uranus was castrated by their son Cronus. The Giants fought Zeus and the other Olympian gods in the Gigantomachy, their epic battle for control of the cosmos. A Giant named Enceladus, fighting Athena, is attested in art as early as an Attic black-figure pot dating from the second quarter of the sixth century BC (Louvre E732). In literature, references to the Giant occur as early as the plays of the fifth-century BC Greek tragedian Euripides, where, for example, in Euripides' Ion, the chorus describes seeing on the late sixth-century Temple of Apollo at Delphi, Athena "brandishing her gorgon shield against Enceladus". Although traditionally opposed by Athena, Virgil and others have Enceladus being struck down by Zeus. In Euripides' comic satyr play Cyclops, Silenus, the drunken companion of the wine god Dionysus, boasts of having killed Enceladus with his spear. The third-century BC poet Callimachus has Enceladus buried under the island of Sicily, and according to the mythographer Apollodorus, Athena hurled the island of Sicily at the fleeing Enceladus during the Gigantomachy. The Latin poets Virgil, Statius and Claudian all locate his burial under Mount Etna, although other traditions had the monster Typhon or the Hundred-Hander Briareus buried under Etna. For some Enceladus was instead buried in Italy. The Latin poet Horace has Enceladus use trees as spears. The second-century geographer Pausanias reports that a Tegean statue of Athena was called "horse goddess" because, according to a local account, Athena "drove the chariot and horses against Enceladus". Claudian calls Enceladus "all powerful king of the Earth-born giants", and has Gaia, imagining the Giants victorious, propose that "Enceladus, rule the sea".

The fifth-century Greek poet Nonnus, in his poem Dionysiaca, mentions Enceladus as one of the several Giants that Dionysus battles in the Gigantomachy. Nonnus has Gaia set the Giants against Dionysus, promising Enceladus Athena as his wife should the Giants subdue Dionysus. Dionysus fought Enceladus with fire, but Enceladus was ultimately defeated by Zeus:"[Dionysus] roasted the Giants' bodies with a great conflagration, an image on earth of the thunderbolt cast by Zeus. The torches blazed: fire was rolling all over the head of Encelados and making the air hot, but it did not vanquish him—Encelados bent not his knee in the steam of the earthly fire, since he was reserved for a thunderbolt."

Enceladus — like Typhon, Briareus and other vanquished monsters thought to be buried under volcanoes — was said to be the cause of earthquakes and volcanic eruptions. Mount Etna's eruptions were said to be the breath of Enceladus, and its tremors to be caused by him rolling over from side to side beneath the mountain. Virgil, the anonymous Aetna poem, and Claudian all develop the image: Enceladus buried under Aetna by Jove's decree, tossing restlessly beneath the ponderous mountain and breathing penal fire, so that when his rebellious shoulders shift their burden the island is shaken and tottering cities sway.

The battle between Athena and Enceladus was a popular theme in Greek vase paintings, with examples from as early as the middle of the sixth century BC. From the description given in Euripides' Ion, the battle was apparently depicted on the late sixth-century BC Temple of Apollo at Delphi. The east pediment of the Old Temple of Athena on the Acropolis of Athens, dating from the late sixth century, prominently displayed Athena standing over a fallen giant, possibly Enceladus. The battle was probably also depicted on the new peplos (robe) presented to Athena on the Acropolis of Athens as part of the Panathenaic festival.

This atlas entry (enceladus-giant) is the earthborn Giant of the Gigantomachy. Apollodorus also names an Egyptian son of Aegyptus called Enceladus — a different figure. The Saturnian moon Enceladus is a modern namesake, not this mythic Giant.