Marcel (Raymond) Theroux is a British novelist and broadcaster. He is the older son of the American travel writer and novelist, . His younger brother, , is a journalist and television reporter.

Born in Kampala, Uganda, Theroux was brought up in Wandsworth, London. After attending a state primary school he boarded at Westminster School. He went on to study English at Clare College of the University of Cambridge and international relations at Yale University. Currently he lives in London and is married. His French last name originates from the region around Sarthe and Yonne in France. It is quite common in Francophone countries and is originally spelled Théroux. His paternal grandfather was French Canadian.

He wrote The Stranger in The Earth and The Confessions of Mycroft Holmes: a paper chase for which he won the Somerset Maugham Award in 2002. His third novel, A Blow to the Heart, was published by Faber in 2006. His fourth, Far North, a future epic set in the Siberian taiga, was published in June 2009. He worked in television news in New York and Boston.

In 2004 he presented The End of the World as We Know It part of the War on Terra television series about climate change on Channel 4, for which he was chosen as presenter precisely because he initially knew nothing about the subject. He even had a preconception about environmentalists being spoilsports opposed to progress. But during his research he became convinced that we face a global problem, on a scale so serious that an expansion of nuclear energy is probably the best solution (choosing the lesser evil). He reached this conclusion partly via the subjects of several interviews, amongst them Gerhard Bertz of insurance agency Munich Re, who indicated that in the past 20 years payments for natural disasters have increased by 500 percent. During another, with Royal Dutch Shell chairman Lord Ron Oxburgh, a PR assistant intervened to curtail