Dirk Jens Nonnenmacher (born 3 June 1963) is a former CEO and chairman of HSH Nordbank. A trained mathematician, Nonnenmacher worked for several private banks before joining HSH Nordbank in 2007. He became chairman in November 2008, succeeding and left the bank in March 2011.
Nonnenmacher studied mathematics and medicine, before receiving his Ph.D. under supervision of in 1990. He earned his habilitation in 1993.