Greg Cornelsen (born 29 August 1952 in Sydney) is a former Australian rugby union footballer who was capped 25 times for the national team, the Wallabies, from 1974 to 1982.
Cornelsen made his international debut for Australia at 21 years of age, when the Wallabies took on the All Blacks in 1974 in Brisbane, which resulted in a 16-all draw.
Over the following two seasons, he played in matches against Scotland, Wales, England and France; all were in Europe and the Wallabies had a tougher time winning.
In one of Cornelsen's greatest moments, he scored four tries in the third test, seeing Australia through to a 30-16 victory, as well as ending a long string of losses against the Kiwis.
Cornelsen was then capped on the 1981-82 Wallaby tour to Europe against Ireland, Wales, Scotland and England and his long test career came to a close in defeat 11-15 at the home of English rugby, Twickenham.