Nicolas Kiefer, a former German professional tennis player. He reached the semi-finals of the 2006 Australian Open and won a Silver medal in Men's Doubles with partner Rainer Schüttler at the 2004 Summer Olympics in Athens. Kiefer's career-high singles ranking was World No. 4

Nicolas Kiefer (born 5 July 1977 in Holzminden, Lower Saxony), is a former German professional tennis player. He reached the semi-finals of the 2006 Australian Open and won a Silver medal in Men's Doubles with partner Rainer Schüttler at the 2004 Summer Olympics in Athens. Kiefer's career-high singles ranking was World No. 4, achieved in January 2000.

In 2009, he represented Germany in the 2009 Hopman Cup together with 19 year old Sabine Lisicki. In the first match he lost against Australia's Lleyton Hewitt 6–7(6) 6–3 6–2 – who had been six months inactive due to an injury. In the second singles match Kiefer lost again, this time to USA's James Blake 7–6(4) 6–7(8) 6–4. Nevertheless, Kiefer won both of the doubles matches together with Sabine Lisicki against both Australia and the United States. On the third singles match, Kiefer twisted his ankle against Slovakia's Dominik Hrbatý in the first set when Kiefer was 3–1 up and serving for 4–1. This injury impeded him to participate in the 2009 Australian Open. He re-appeared in the 2009 Davis Cup match against Austria in which he won in the doubles match together with Philipp Kohlschreiber against Julian Knowle and Alexander Peya in 4 sets 6–3 7–6(6) 3–6 6–4. Kiefer also played a singles match, the fourth match, against Jürgen Melzer in which Kiefer won in straight sets 7–6 6–4 6–4 and gave Germany the victory against Austria. Kiefer then participated in the 2009 BNP Paribas Open at Indian Wells in which he beat Bobby Reynolds in straight sets 6–4 6–2 in Second Round, but he then lost in Third Round to Andy Roddick 6–4 7–6(4).