Olen was a legendary early poet from Lycia who went to Delos, where his hymns celebrating the first handmaidens of Apollo in the island of the god's birth and other "ancient hymns" were still part of the cult at Delos in the time of Herodotus: Arge and Opis came at the same time as the gods of Delos and are honoured by the Delians in a different way. Wikipedia