Iolaiis was a son of Iphicles and Automedusa. He was also the nephew of Heracles and professionally was his charioteer. For his constant loyalty to Heracles and to the descendants of the hero we can perhaps see in his name a reference to the two meanings of laos, 'people', 'subjects' and 'of stone' (laos is a genitive oïlaas). He is thus a 'rock of the people'.