Neleus was a son of Poseidon and Tyro. He was the twin brother of Pelias and he married Ghloris, who bore him twelve sons and one daughter, Pero. Although his name suggests 'pitiless', from neles (meaning this), it is very tempting in view of all the 'watery' associations in the family to equate his name with that of Nereus and derive it from nao, 'to flow'.

The head of the family tree is Aeolus, whose winds are needed for ships. Aeolus's son was Salmoneus, whose name could mean 'seaman' (see his name). Salmoneus' daughter was Tyro (maybe 'wearer away' like the sea) who became the wife of Poseidon, god of the sea.

On the other hand modern evidence of his name in the Linear Β tablets suggests that Neleus is a shortened form of Mycenaean Nehe-lawos, meaning 'saving the people'. There was apparently a real Neleus whose father Codrus was a king of Athens and saved the city from attack by the Dorians.