Michael Henry Knox Irwin (born 5 June 1931) is a British doctor, formerly a GP and a Medical Director with the United Nations. He is a humanist and secular activist, campaigning in particular for Voluntary Euthanasia and Doctor-Assisted Suicide.
Irwin was trained at St. Bartholomew's Hospital Medical College, London (graduating in 1955), and at Columbia University, New York. He was awarded a master's degree in public health from the latter in 1960.
He worked at Prince of Wales Hospital, London, from 1955-1956. In 1957 he became Medical Officer at the United Nations. In 1961 he worked with the UN in Pakistan, returning to his Medical Officer post in 1963 and rising to become Medical Director of the United Nations in 1969. He became Director of Personnel at the United Nations Development Programme in 1973. In 1977, he was the UNICEF Representative in Bangladesh. From 1980 to 1982, Irwin was the UNICEF Senior Adviser on Childhood Disabilities. In 1982, he returned to the United Nations to become Medical Director again. In 1989 and 1990, he was the Medical Director for the World Bank and the IMF.
He was struck off by the UK General Medical Council in 2005 after openly admitting travelling to the Isle of Man in October 2003 to assist fellow campaigner Patrick Kneen to end his life. Irwin was arrested by the Isle of Man police for this activity in December 2003, but he was never charged.
In April 1990 Irwin resigned from the World Bank. He wrote an article for The Wall Street Journal which detailed his complaints about the Bank. He cited in particular "the Bank's bloated, overpaid bureaucracy, its wasteful practices, and its generally poor management."
Returning to the UK in 1993, Irwin became the Vice-Chairman of the United Nations Association in 1995, and its Chairman from 1996 to 1998.
Irwin is an active supporter of euthanasia, humanism and secularism. He was interviewed by Ritula Shah about such matters in the BBC Radio 4 series One to One on 21 May 2013.
From 1995 to 2003, Irwin was either the Vice-Chairman or the Chairman of the Voluntary Euthanasia Society (now, renamed Dignity in Dying).