Ewan McCrimmon was the cousin of Donald McCrimmon. He lived in Rowlands Gill, in Scotland during the 13th century.
Jamie McCrimmon met Ewan during his travels with the Second Doctor and Victoria Waterfield. Jamie told him that he was the son of Donald McCrimmon, with Ewan assuming that he meant his cousin Donald, to whom he admitted Jamie bore a resemblance. (PROSE: On a Pedestal)