James O'Brien
John O'Brien
Kennedy O'Brien
Michael O'Brien
Richard Ocock
Daniel O'Connor
Patrick O'Day
Michael O'Dea
James Oddie
James O'Donnell
Patrick O'Donoghue
John Ogier
James O'Grady
John O'Meara
O'Neil, Abbott
O'Neil, Benjamin
O'Neil, James
O'Neil, Minchin
John O'Neil
Michael O'Neill
Richard O'Neil
Thomas O'Neill
Matthew Orr
George Osborne
Robert Osborn
John O'Shannessy
John O'Toole
William Otway
John Owens
Francis Oxley