Karel Effa, originally named Karel Effenberger (May 23, 1922 in Prague - June 11, 1993 in Prague), was a Czech actor.

As a professional soldier during World War II, he served in the Government Army during the Protectorate of Bohemia and Moravia, which was deployed to Italy. Here he later ran to the Czechoslovak troops fighting on the side of the Western Allies. After the war, he remained in the army with the rank of sergeant, playing and singing for two years in the newly formed Army Art Ensemble of Vít Nejedlý. From there he went to the Theater of Satire, from there to the Theater of State Film, from there to the Music Theater in Karlín, from where he briefly jumped to the ABC Theater to return to the Karlín Theater. He has been a member of the Semafor Theater since 1979.