Olus was the twin brother of Eurybatus, the two being the cheating, lying Cercopes who plagued Heracles (and constantly robbed him). The name may be a contraction of olesypnos, meaning 'sleep destroying' (from ollymi, 'to destroy' and hypnos, 'sleep'), on the lines of other 'destroying' words starting oles- such as olesibolos, 'earth-destroying' and olesioicos, 'house-destroying'.
