Nima Arkani-Hamed (born 5 April 1972) is a Canadian/American theoretical physicist with interests in high-energy physics, string theory and cosmology. Formerly a professor at Harvard, Arkani-Hamed is now on the faculty at the Institute for Advanced Study at Princeton.

Arkani-Hamed graduated from the University of Toronto with a Joint Honours degree in mathematics and physics, and went to the University of California, Berkeley for his graduate studies, where he worked under the supervision of Lawrence Hall. He completed his PhD in 1997 and went to SLAC at Stanford University for post-doctoral studies. During this time he worked with Savas Dimopoulos on large extra dimensions.

In 1999 he joined the faculty of the University of California, Berkeley Physics Department. He took a leave of absence from Berkeley to visit Harvard University beginning January 2001. Shortly after arriving at Harvard he worked with Howard Georgi and Andrew Cohen on the idea of emergent extra dimensions, dubbed dimensional deconstruction. These ideas eventually led to the development of little Higgs theories. He officially joined Harvard's faculty in the fall of 2002.

Arkani-Hamed has appeared on various television programs and newspapers talking about space, time and dimensions and the current state of theoretical physics. In 2003 he won the Gribov Medal of the European Physical Society, and in the summer of 2005 while at Harvard he won the 'Phi Beta Kappa' award for teaching excellence.