Ludwig Josef Johann Wittgenstein (pronounced ) (26 April 1889 – 29 April 1951) was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. As one of the twentieth century's most important philosophers, his influence has been wide-ranging.

Before his death at the age of 62, the only book-length work Wittgenstein had published was the Tractatus Logico-Philosophicus . Philosophical Investigations , which Wittgenstein worked on in his later years, was published shortly after he died. Both of these works are regarded as highly influential in analytic philosophy.