Bryan Campbell Clarke FRS (24 June 1932 – 27 February 2014) was a British Professor of genetics, latterly emeritus at the University of Nottingham. Clarke is particularly noted for his work on apostatic selection (which is a term he coined in 1962) and other forms of frequency-dependent selection, and work on polymorphism in snails, much of it done during the 1960s. Later, he studied molecular evolution. He made the case for natural selection as an important factor in the maintenance of molecular variation, and in driving evolutionary changes in molecules through time. In doing so, he questioned the over-riding importance of random genetic drift advocated by King, Jukes, and Kimura. With Professor James J Murray Jnr (University of Virginia), he carried out an extensive series of studies on