This study deals with the relationship between Lugus, the main god of the Celts, and the equine family throughout the Celtic area. In Celtiberic Spain, Lugus was called 'equeisos' - that is equestrian or equine. In Gaul, this divinity appeared as the Roman Mercurius and Apollo ; it was given the name of 'Atepomaros' (meaning 'Great Horse'), who founded under this name the town of Lugudunum/Lyons. Broadly speaking, Lugus was also the charioteer that leads horses on most Gallic coins : as such, he was sometimes represented with a solar face or an extensive forearm, a characteristic peculiar to him. This solar charioteer is still found on a Gallo-Roman bronze struck around 266-267 AD, which represents Lugus leaping forward with his spear whilst pulling a horse behind him. The god was also worshipped in Northern Italy and in Gaul under the name of Belenos, 'the Shining', who was linked to a divine horse on Gallic coins. Finally, Lugus was associated in an iconographie and functional way with Epona, 'the (divine) Mare', with whom he protected travellers in particular. For the Celtic islanders, Lugh was the first horseman, who created horse riding and founded horse racing. He was closely linked to the horse goddess (Macha in Ireland and Rhiannon, 'the Great Queen', in Wales), the embodiment of sovereignty, of whom, as a foal, he appears to be the son. In this connection, he could be the twin brother of a sea-creature. Lugh also had relationships with equine women, which may be the expression of some Irish rites of royal consecration. This is confirmed by clear Indo-European parallels in which equine sexuality plays a central role and the presence of the divinity is perceptible.