British philosopher, logician, essayist, and social critic, best known for his work in mathematical logic and analytic philosophy. His most influential contributions include his defense of logicism (the view that mathematics is in some important sense reducible to logic), and his theories of definite descriptions and logical atomism. Along with G.E. Moore, Russell is generally recognized as one of the founders of analytic philosophy. Along with Kurt Gödel, he is also regularly credited with being one of the two most important logicians of the twentieth century.

Over the course of his long career, Russell made significant contributions, not just to logic and philosophy, but to a broad range of other subjects including education, history, political theory and religious studies. In addition, many of his writings on a wide variety of topics in both the sciences and the humanities have influenced generations of general readers. After a life marked by controversy (including dismissals from both Trinity College, Cambridge, and City College, New York), Russell was awarded the Order of Merit in 1949 and the Nobel Prize for Literature in 1950. Also noted for his many spirited anti-war and anti-nuclear protests, Russell remained a prominent public figure until his death at the age of 97.