Mark Thatcher, English businessman
Sir Mark Thatcher, 2nd Baronet (born 15 August 1953) is an English businessman. He is the son of Margaret Thatcher, Prime Minister of the United Kingdom from 1979 to 1990, and Sir Denis Thatcher, and is the twin brother of Carol Thatcher.

His early career in business led to suggestions that he was benefiting from his mother's position, notably in relation to the Al-Yamamah arms deal. He left the UK in 1986, and has since lived in the United States, Switzerland, Monaco, South Africa, Gibraltar, Barbados, Guernsey, and Spain. In 2004 the Sunday Times estimated his wealth at £60 million, most of which was suggested to be in offshore accounts.

In 2005, he was convicted and given a four-year suspended prison sentence and fined in South Africa for funding the 2004 Equatorial Guinea coup d'état attempt.

He has two children by his first wife, Diane Burgdorf. He wed his second wife, Sarah-Jane Russell (née Clemence), in 2008. After his father's death in 2003, he became Sir Mark Thatcher and succeeded to the Thatcher baronetcy, a hereditary title which had unusually been given to his father in 1990 (this being the only baronetcy created since 1964).