Jennifer Denise Key is a retired South African mathematician whose research has concerned the interconnections between group theory, finite geometry, combinatorial designs, and coding theory. She is a professor emeritus at Clemson University in the US, and an honorary professor at Aberystwyth University in the UK, and the University of KwaZulu-Natal and University of the Western Cape in South Africa.
Key graduated with honours from Rand Afrikaans University in 1963, and went to the University of London for graduate study in mathematics, earning a master's degree in 1968 and comleting her Ph.D. in 1970. Her dissertation, Some Topics in Finite Permutation Groups, was jointly supervised by Ascher Wagner and Kurt Hirsch.
She worked as an academic in England, at the University of Surrey, University of Reading, University of Manchester, and University of Birmingham, before moving to the US in 1990 to take a faculty position at Clemson University. She retired as professor emeritus in 2007.
Key is the author, with Edward F. Assmus Jr., of the book Designs and Their Codes (Cambridge University Press, 1992).