Jean-Jacques Cassiman (25 April 1943 – 5 August 2022) was a Belgian geneticist and professor of human genetics.

Jean-Jacques Cassiman has done work in the field of human genetics and DNA research.

In 1998 Professor Cassiman proved through DNA testing that Karl Wilhelm Naundorff was not a descendant of the Bourbons and certainly not Louis XVII.

In the first half of the 1960s, he was a singer in the Trio Cassiman that he together with his brother Guido and his sister Emmy formed.

The trio played folk music and negro spirituals, and was regularly seen on the Flemish podiums.