Susan O'Neill, AM (born 2 August 1973) is an Australian former competitive swimmer from Brisbane, Queensland, nicknamed "Madame Butterfly".

[3] On 10 March 2007 during the 12th FINA World Championship, O'Neill was honoured by the dedication of the temporary swimming pool in the Rod Laver Arena in Melbourne named after her for the duration of the competition.

[6] In May 2019, O'Neill was announced as Australia's joint Deputy Chef de Mission for the 2020 Olympic Games in Tokyo,[7] with fellow Olympians, Evelyn Halls and Kim Brennan.

O'Neill and her husband, Cliff Fairley, help generously to raise awareness for the Fred Hollows Foundation, and are one of its most distinguished ambassadors.

[19] The Fred Hollows Foundation is an international nonprofit organisation that educates surgeons on how to cure avoidable blindness within underserved communities and countries.