Onomaris
Onomaris was a Celtic woman who is described in the anonymous collection of Greek stories known in Latin as Tractatus De Mulieribus Claris en Bello. According to this text source, her people, suffering from scarcity and needing to flee their land, offered to obey anyone willing to lead them. When no man accepted the offer, Onomaris pooled their resources and led the emigration. Onomaris crossed the Ister and ruled over the land after defeating the local inhabitants in battle. She is estimated to have lived at around the 4th century BC. She was honored by the Galatians for her  feats. The name Onomaris sounds like a Greek word but it appears to be a compound, with the second element "-maris" reflecting a Celtic root that meant "great". It may also mean "mountain ash", or possibly "like a great mountain ash or rowan tree". It is also suggested that the "on" or "on(n)o" in her name meant "river".