David Gregory Smith (born 24 July 1955) is a retired male race walker from Australia, who represented his native country at two consecutive Summer Olympics, starting in 1980 (Moscow). His best Olympic result was finishing in tenth place in the men's 20 km race at the 1984 Summer Olympics.
Smith won the British AAA Championships title in the 3000 metres walk event at the 1983 AAA Championships.
His son, Dane Bird-Smith, also became an international walker for Australia.