Ó Dálaigh, Seán(1987 - ) Ireland
Ó Riada, Seán(1931 - 1971) Ireland
O'Boyle, Sean(1963 - ) Australia
O'Brien, Benjamin(? - ) USA
O'Brien, JoyEllen(? - ) USA
O'Callaghan, James(1988 - ) Canada
O'Connell, Katharine(1971 - ) USA
O'Connell, Kevin(1958 - ) Ireland
O'Connor, Cameron(? - ) USA
O'Connor, Neil(1979 - ) Ireland
O'Connor, Patrick Stephen(1988 - ) Ireland
O'Connor, Simon(1975 - ) Ireland
O'Doherty, Brian(? - )
O'Dwyer, Timothy(1971 - ) Australia
O'Halloran, Emma(? - ) Ireland
O'Halloran, Sarah(1983 - ) Ireland
O'Halpin, Barry(? - ) Ireland
O'Keeffe, Eoin(1979 - ) Ireland
O'Leary, Jane(1946 - ) Ireland
O'Leary, Martin(1963 - ) Ireland
O'Neill, Nicholas(1970 - ) United Kingdom
O'Regan, Tarik(1978 - ) United Kingdom
O'Riordan, Kirk(1968 - ) USA
Oberholtzer, Josiah Wolf(1984 - ) USA
Obermaier, Klaus(1955 - ) Austria
Obermayer, Klaus(1943 - 2009) Germany
Obermüller, Karola(1977 - ) Germany
Obieglo, Lorenz(1894 - 1977)