Neil Geoffrey Turok (born 1958 in Johannesburg, South Africa) is the Director of Perimeter Institute for Theoretical Physics. He is the son of Mary and Ben Turok, activists in the anti-apartheid movement and the African National Congress.

After graduating from Churchill College, Cambridge, Turok gained his doctorate from Imperial College, London, under the supervision of Professor David Olive, one of the inventors of superstring theory. After a postdoctoral post at Santa Barbara, he was an associate scientist at Fermilab, Chicago. In 1992 he was awarded the Maxwell medal of the Institute of Physics for his contributions to theoretical physics. In 1994 he was appointed Professor of Physics at Princeton University, then held the Chair of Mathematical Physics at the University of Cambridge starting in 1997. He was appointed Director of the Perimeter Institute in 2008.

Turok has worked in a number of areas of mathematical physics and early universe physics, focusing on observational tests of fundamental physics in cosmology. In the early 1990s, his group showed how the polarisation and temperature anisotropies of the cosmic background radiation would be correlated, a prediction which has been confirmed in detail by recent precision measurements by the WMAP spacecraft. They also developed a key test for the presence of a cosmological constant, also recently confirmed. Turok and collaborators developed the theory of open inflation. With Stephen Hawking, he later developed the so-called Hawking-Turok instanton solutions which, according to the no-boundary proposal of Hawking and James Hartle, can describe the birth of an inflationary universe.