Simon Paul Poidevin (born 31 October 1958) is a former Australian rugby union player.
Poidevin made his Test debut for Australia against Fiji during the 1980 tour of Fiji.
He was a member of the Wallabies side that defeated New Zealand 2–1 in the 1980 Bledisloe Cup series.
He toured with the Eighth Wallabies for the 1984 Australia rugby union tour of Britain and Ireland that won rugby union's "grand slam", the first Australian side to defeat all four home nations, England, Ireland, Wales and Scotland, on a tour.
He made his debut as captain of the Wallabies in a two-Test series against Argentina in 1986, substituting for the absent Andrew Slack.
He was a member of the Wallabies on the 1986 Australia rugby union tour of New Zealand that beat the New Zealand 2–1, one of five international teams and second Australian team to win a Test series in New Zealand.
During the 1987 Rugby World Cup, he overtook Peter Johnson as Australia's most capped Test player against Japan, captaining the Wallabies for the third time in his 43rd cap.
He captained the Wallabies on a fourth and final occasion on the 1987 Australia rugby union tour of Argentina before injury ended his tour prematurely.
In 1988, he briefly retired from international rugby, reversing his decision 42 days later ahead of the 1988 Bledisloe Cup series.
Following this series, Poidevin continued to make sporadic appearances for the Wallabies, which included a return to the Australian side for the single 1989 Bledisloe Cup Test.
After making himself unavailable for the 1990 Australia rugby union tour of New Zealand, he returned to the Australian national squad for the 1991 season.
Poidevin was a member of the Wallabies that won the 1991 Rugby World Cup, after which he retired from international rugby union.
Poidevin is one of only four Australian rugby union players, along with David Campese, Michael Lynagh and Nick Farr-Jones, to have won rugby union's Grand Slam, achieved a series victory in New Zealand, and won a Rugby World Cup.