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