Celtic god of Gaul identified with the Roman Hercules. He was portrayed as an old man with swarthy skin and armed with a bow and club. He was also a god of eloquence, and in that aspect he was represented as drawing along a company of men whose ears were chained to his tongue.

Ogmios' Irish equivalent was Ogma, whose Herculean, warlike aspect was also stressed. In Irish tradition he was portrayed as a swarthy man whose battle ardour was so great that he had to be controlled by chains held by other warriors until the right moment. Ogham (ogham writing) script, an Irish writing system dating from the 4th century AD, seems to have been named for him, a fitting association for a god of eloquence.