David Ernest Oldfield (born 25 June 1958) is a former Australian politician who co-founded and was deputy leader of the Pauline Hanson’s One Nation party. Oldfield was initially involved in politics as a member of the City of Manly Council, a Liberal candidate for Manly and a political advisor to then-Liberal Party minister (and future Prime Minister of Australia), Tony Abbott.

He later became acquainted with parliamentary newcomer Pauline Hanson, who in the wake of her election to the Australian House of Representatives gained notoriety for comments about Indigenous Australians, Asians, immigration and multiculturalism. While working for Abbott, Oldfield began to construct Pauline Hanson’s One Nation. One Nation was formed in 1997, and Oldfield was appointed an informal deputy leader, serving with David Ettridge.

In 2000 Oldfield was expelled from One Nation after a dispute with Hanson and formed the splinter group One Nation NSW, serving as its leader from its creation in 2000, to its dissolution in 2004. Oldfield was a member of the New South Wales Legislative Council from 1999 to 2007, under One Nation, One Nation NSW and briefly as an independent twice. In 2006, Oldfield announced that he would not recontest the 2007 New South Wales election. Today, he lives in Sydney with his family. He formerly hosted radio programs on radio 2UE and radio 2GB.