Douglas Keith Armstrong QSO is a former city councillor on the Auckland City Council, New Zealand for the Citizens & Ratepayers ticket.
Armstrong was first elected in 2001 for the Citizens & Ratepayers ticket, and served as the chairman of finance at Auckland City between 2001–2004 and 2007 onwards. He was also the deputy leader of the Citizens & Ratepayers ticket from October 2004, serving under the leadership of David Hay.
In October 2010 Armstrong unsuccessfully stood as a Citizens & Ratepayers candidate on the Orākei ward of the new Auckland Council: he was defeated by Cameron Brewer, an independent.
Prior to his election as councillor for the centre-right Eastern Bays ward, Armstrong was the chief executive officer of Unitec, one of Auckland's polytechnical institutes. He was trained as a civil engineer and is a past president of the Institution of Professional Engineers New Zealand and former member of the Prime Minister's Enterprise Council.
In the 1996 Queen's Birthday Honours Armstrong was appointed a Companion of the Queen's Service Order for public services. He is also a trustee of the Sir Woolf Fisher Trust for excellence in education.