Daniel Stuart "Dan" Freed (born 17 April 1959) is an American mathematician, who specializes in global analysis and its applications to supersymmetry, string theory, and quantum field theory.
Freed studied at Harvard University, where he received his bachelor's and master's degrees in 1981. He received his PhD from the University of California, Berkeley with thesis The geometry of loop groups under Isadore Singer. As a postdoc Freed was a Moore Instructor at MIT and then became an assistant professor at the University of Chicago. Beginning in 1989 he was an associate professor and from 1994 a professor at the University of Texas at Austin. From 1996 to 1998 he was at the Institute for Advanced Study (IAS) and he was a visiting scientist at IHES (1995, 1999).
In the academic year 2002/2003 Freed was a Guggenheim Fellow and from 1988 to 1992 a Sloan Fellow. In 2002 he was an invited speaker at the International Congress of Mathematicians in Beijing (Twisted K-theory and loop groups). He is one of the founders of the IAS/Park City Mathematics Institute and is since 2006 a member of the board of trustees of MSRI, where he has belonged to the scientific advisory board since 2002. He is a Fellow of the American Mathematical Society.