Nephus is the son of Herakles and Praxithea who is one of the daughters of King Thespius. During his stay in the court of King Thespius Herakles impregnated 49 of 50 Thespius' daughters including Praxithea who he lay with one night. The result of that particular encounter was Nephus.
"by Praxithea he [Herakles] had Nephus
- Apollod. Biblioteca 2.7.8