Who's the most influential thinker ever?

A study suggests that Marx is the most influential scholar in the west, followed by Freud, but tell us who had the most effect on you

theguardian.com, Thursday 7 November 2013 11.44 GMT

An algorithm devised by researchers at the Indiana University Bloomington has indicated that Karl Marx is the most influential scholar in western academia. Snapping at his heels is the psychoanalyst Sigmund Freud, followed by the physicist Edward Witten and philosopher Jacques Derrida.

Which thinker in your view has had the most influence over the world we live in today? Alternatively, tell us who has most influenced your life – be it a theorist, academic or popular writer.