Karel Rachůnek (born August 27, 1979 in Gottwaldov, Czechoslovakia) is a Czech professional ice hockey defenceman currently playing for HC Dynamo Moscow of the Kontinental Hockey League (KHL). He was drafted in the ninth round, 229th overall, by the Ottawa Senators in the 1997 NHL Entry Draft.
Drafted out of the Czech Extraliga's HC Zlín, Rachůnek made his North American debut with the Grand Rapids Griffins of the International Hockey League during the 1999–2000 season. He made his National Hockey League debut during the same season, appearing in six games for the Senators. The following season, he made the Ottawa roster out of training camp and was a regular in the Senators' lineup from 2000–01 until 2003–04, when a trade deadline deal sent him, along with Alexandre Giroux, to the New York Rangers in exchange for Greg de Vries. An earlier contract dispute was rumoured to have hastened his departure from Ottawa.
During the 2004–05 NHL lockout, Rachůnek returned to the Czech Extraliga to play for HC JME Znojemští Orli. He remained in Europe for the 2005–06 season, playing in the Russian Superleague for Lokomotiv Yaroslavl. It was reported that Rachůnek was unhappy with the circumstances surrounding his trade from Ottawa to the Rangers, and that is why he decided to stay in the RSL during the 2005–06 season. However in July 2006 he signed with the Rangers and played with them during the 2006–07 NHL season.