David G. Blair (born 1946) is an Australian physicist and professor at the University of Western Australia and Director of the Australian International Gravitational Research Centre. Blair works on methods for the detection of gravitational waves. He developed the niobium bar gravitational wave detector NIOBE, which achieved the lowest observed noise temperature, and participated in a worldwide collaboration that set the best limit on the burst events in 2001. He has been responsible for numerous innovations including the 1984 invention of the first sapphire clock, a super-precise timepiece designed for space, as well as underpinning the research of the Frequency Stability Group at The University of Western Australia.