Sir Donal Arthur John Keegan, KCVO, OBE (born 1938) is a Northern Irish physician and public servant.

Born in 1938, Keegan studied medicine at Queen's University Belfast, graduating in 1961 with a BSc degree and three years later with an MB BCh BAO degrees. In 1970, he became a consultant physician on the Highland and Western Isles Health Board; five years later, he moved to Altnagelvin Hospital, where he worked until 2003.^[1] In 1999, he was appointed an Officer of the Order of the British Empire "for services to rehabilitation services".^[2] He has also been a Fellow of the Royal College of Physicians of Ireland since 1973 and a Fellow of the Royal College of Physicians since 1990.^[1]

Keegan served on a number of organisations, including as chairman of the Regional Advisory Committee on Cancer from 1997 to 2005. Between 2002 and 2013, he was Lord Lieutenant of the City of Londonderry.^[1] For this service, he was appointed a Knight Commander of the Royal Victorian Order in the 2012 Birthday Honours.^[3]