Justin O'Byrne | |
|---|---|
 O'Byrne in 1970 | |
| Senator for Tasmania | |
| In office 1 July 1947 – 30 June 1981 | |
| President of the Australian Senate | |
| In office 9 July 1974 – 11 November 1975 | |
| Preceded by | Sir Magnus Cormack |
| Succeeded by | Condor Laucke |
| Personal details | |
| Born | 1 June 1912 Launceston, Tasmania, Australia |
| Died | 10 November 1993 (aged 81) Launceston, Tasmania, Australia |
| Political party | Australian Labor Party |
| Military service | |
| Allegiance | Australia |
| Branch/service | Royal Australian Air Force |
| Years of service | 1940–1946 |
| Rank | Flight lieutenant |
| Unit | No. 452 Squadron RAAF |
Justin Hilary O'Byrne, AO (1 June 1912 – 10 November 1993) was an Australian politician who served as a Senator for Tasmania from 1947 to 1981, representing the Australian Labor Party (ALP). He was President of the Senate from 1974 to 1975, including for the duration of the 1975 constitutional crisis that resulted in the dismissal of the Whitlam government.