David Marshall Sadleir AO (born 20 February 1936) is an Australian business consultant and former diplomat and ambassador, who was Director-General of Security (head of the intelligence agency ASIO) from 1992 to 1996.
[1] Sadleir joined the Australian Department of External Affairs in 1958.
He was an advisor to the Australian delegations to the Inter-Parliamentary Union, and was posted in Tokyo and Washington DC as Assistant Secretary of the department's North Asia branch.
He was a Permanent Representative to the United Nations and other international organisations in Geneva from 1981 to 1984.
[1] In 1998, he conducted a review of Australia's entry control arrangements, in particular the Movement Alert List (MAL).