David Oliver Tonkin AO (20 July 1929 – 2 October 2000) was an Australian politician who served as the 38th Premier of South Australia from 18 September 1979 to 10 November 1982.

Accepted into Medicine at the University of Adelaide, Tonkin worked as a taxi driver while completing his degree and practised as a General Practitioner before undertaking a postgraduate ophthalmology course in London.

Tonkin gained statewide prominence in 1974, when he successfully introduced a private member's bill to outlaw sex discrimination, the first such law in Australia.

A year later, this prominence led him to challenge Bruce Eastick for the leadership of what by then had become the South Australia branch of the Liberal Party.

At the time, this was the largest two-party victory for any party since the end of the Playmander, exceeding Labor taking 54.5 percent in 1973.

Already governing on a knife-edge, Tonkin's majority became even slimmer in 1980 after a court decision threw out a Liberal victory in Dunstan's old seat Norwood, and Labor regained it in the ensuing by-election.

Also serving as his own state Treasurer, Tonkin combined fiscal conservatism with implementing socially progressive reforms.

In the former, Tonkin made significant cuts to the public service, earning him the enmity of the unions, while an example of the latter was the passage of the land rights bill and the return to the Pitjantjatjara people of 10 per cent of South Australia's area.

Subsequently, Tonkin returned to ophthalmology and served in various capacities in different government and community organisations, including chairman of the board of the State Opera from 1985 to 1986 and vice-president of Sturt Football Club.

In addition, a Memorial Dinner in his name is also now held each year by The South Australian Young Liberal Movement.