Augustine Thomas O'Donnell, Baron O'Donnell, GCB, FBA, FAcSS (born 1 October 1952) is a former British senior civil servant and economist, who between 2005 and 2011 (under three Prime Ministers) served as the Cabinet Secretary, the highest official in the British Civil Service.

[1][2] His post was then split into three positions: he was succeeded as Cabinet Secretary by Sir Jeremy Heywood, as Head of the Home Civil Service by Sir Bob Kerslake (in a part-time role), and as Permanent Secretary in the Cabinet Office by Ian Watmore.

[3][4] Whilst Cabinet Secretary, he was regularly referred to within the Civil Service, and subsequently in the popular press, as GOD; this was mainly because of his initials.

From 1997 to 1998, O'Donnell was the United Kingdom's executive director to both the International Monetary Fund and the World Bank, again in Washington, before returning to HM Treasury to serve as both director of Macroeconomic Policy and Prospects and also head of the Government Economics Service, with overall responsibility for the professional economists in Her Majesty's Government.

[8] Three years later, on 15 June 2005, it was announced that O'Donnell would again replace Turnbull, this time as Cabinet Secretary, on the latter's imminent retirement.

[12] During his time as Cabinet Secretary, his authority was seen as absolute, giving rise to the affectionate nickname "GOD" based on his initials as they appeared in Government papers.

[14] In his role as Cabinet Secretary, O'Donnell was responsible for overseeing the review of Christopher Meyer's controversial memoirs, DC Confidential, in November 2005.

The previous month he had told the Public Administration Select Committee that it was "wrong" for civil servants to publish personal memoirs.

[15] In January 2011, it emerged that O'Donnell had decided not to publish correspondence sent between Tony Blair and George W Bush prior to the 2003 invasion.

[19] On 22 December 2011, O'Donnell said that the future of the Union is one of several "enormous challenges" facing the political establishment in the coming years.

"[34] O'Donnell is a keen sportsman, having played football for the University of Warwick First XI and for Oxford, earning two Blues in 1973/4 and 1974/5.