Bertrand Arthur William Russell, the 3rd Earl Russell, was a British philosopher, logician, mathematician, and public intellectual. He was a prominent figure in the development of mathematics, logic, set theory, and various areas of analytic philosophy. As one of the early 20th century's leading logicians, he was considered a founder of analytic philosophy.

Russell, along with his predecessor Gottlob Frege, his friend and colleague G. E. Moore, and his student and protégé Ludwig Wittgenstein, led the British "revolt against idealism." Together with his former teacher A. N. Whitehead, Russell co-authored Principia Mathematica, a milestone in classical logic and a significant attempt to reduce all mathematics to logic, a concept known as logicism. Russell's article "On Denoting" is considered a philosophical paradigm.

Beyond his academic contributions, Russell was a committed pacifist and social reformer. He championed anti-imperialism and chaired the India League. Russell faced imprisonment during World War I for his pacifism and later supported appeasement against Nazi Germany, before ultimately advocating for war as a necessary evil in 1943. After World War II, he endorsed American global leadership over Soviet hegemony, despite potential nuclear consequences. Russell was a vocal critic of Stalinist totalitarianism, opposed the United States' involvement in the Vietnam War, and was an ardent proponent of nuclear disarmament.

In 1950, Russell was awarded the Nobel Prize in Literature for his extensive and influential writings, which championed humanitarian ideals and freedom of thought. He also received several other honors, including the De Morgan Medal (1932), Sylvester Medal (1934), Kalinga Prize (1957), and Jerusalem Prize (1963).