Dirk Dier (born 16 February 1972) is a former professional tennis player from Germany.

[1] In 1990, he defeated Leander Paes to win the boys' singles event in the Australian Open and also finished runner-up in the juniors at Queen's that year.

He appeared in the main draw of a Grand Slam for the first time at the 1990 Wimbledon Championships, where he lost in the opening round to countryman Michael Stich.

[2] Dier made just one quarter-final during his career on the ATP Tour, which was in the 1996 Bermuda Open.

En route he defeated two top 100 players, Michael Joyce and Nicolás Lapentti.