Hans Gerard Kaper (born June 10, 1936) is a Dutch-American mathematician who worked for many years at Argonne National Laboratory until his retirement in 2008. He continues to hold adjunct professorships in mathematics and statistics at Georgetown University and in music at the University of Illinois at Urbana–Champaign, where he has been a long-term collaborator on the UIUC Computer Music Project. In 2009, Kaper and his son Tasso J. Kaper (a mathematician at Boston University) were simultaneously honored as fellows of SIAM.