Robert Brown (Robby) Gardner (Tarrytown, New York, February 27, 1939 – May 5, 1998) was an American mathematician who worked on differential geometry.

He joined the faculty of the University of North Carolina at Chapel Hill in 1971 and became a full professor there in 1977.

[4] His 1991 book, Exterior Differential Systems, coauthored with R. Bryant, S. S. Chern, H. Goldschmidt, and P. Griffiths, is the standard reference for the subject.

[1] He is better known in the United States for his improvements and popularization of the methods of Élie Cartan (most notably, Cartan's equivalence method, an algorithmic procedure for determining if two geometric shapes are different).

[6][7] In his memory, the UNC Mathematics Department created the Robert Brown Gardner Memorial Fund, devoted to supporting graduate student activities.