Mac Oitir
Mac OITIR—V—M'Cottyr, M'Cottir, MacCotter, MacCottier, MacCottar, Cotter, Otterson; 'son of Ottar' (a Norse personal name); the name of an old and respectable family, doubtless of Norse origin, seated at Carrigtwohil, near the city of Cork; also an Ulster surname; generally written Mac Coitir, owing to the attraction of the c of Mac over to the second part of the surname.
Alphabetical Index to Irish Surnames