Ian Derek Marchant (born 9 February 1961) is an English accountant and businessman.
He was the Chief executive officer of Scottish and Southern Energy from 2002 to June 2013, and was chairman of Thames Water from 2018 to July 2023.
Born in Croydon, Marchant attended the independent Trinity School of John Whitgift.
Afterwards he studied at Durham University, as a member of Hatfield College, gaining a 2:1 in Economics in 1983.
He is also chair of Logan Energy[5] and a non-executive director of Aggreko, and a past chairman of John Wood Group, Nova Innovation and Infinis.