In Norse mythology, Gymir was a giant whose daughter, Gerðr, married the god Freyr.
According to the Eddic poems Skírnismál and Hyndluljóð, Gymir and his wife Aurboða are Gerð's and her brother Beli's parents. He is also listed as a distinct cousin to Thjazi. In the Prose Edda, Snorri Sturluson gave this information in Gylfaginning but in a list of kennings in Skáldskaparmál equates Gymir with the god and giant Ægir, citing a verse by Hofgarða-Refr Gestsson where the kenning in question probably simply substitutes one giant-name for another. Gymir is also equated with Ægir in the prose introduction to Lokasenna; however, the Nafnaþulur added later to the Prose Edda list him among the giants. He is credited to live in a great house in Jotunheim surrounded by dogs. Gymir has usually been interpreted as a sea-giant, but Magnus Olsen regarded him as an earth giant in connection with his interpretation of Skírnismál in light of the hieros gamos and he has also been seen as a chthonic deity. Suggestions as to the etymology and meaning of his name include 'earthman', 'the wintry one', 'the protector' and 'the bellower'.
According to John Lindow, one source calls Gerð's father Geysir.