Susannah "Susie" Hennessy O'Reilly (25 January 1881 – 18 June 1960) was a family doctor and obstetrician who practiced on the North Shore in Sydney in the first half of the 20th century.
Despite graduating fourth in her year from Medicine at the University of Sydney, her application for residency at Sydney Hospital in 1905 was rejected in favour of male applicants with a poorer academic record.