Karel Třešňák (born February 21, 1949 in Karlovy Vary) is a former Czechoslovak slalom canoeist who competed in the 1970s. He won seven medals at the ICF Canoe Slalom World Championships with two golds (C-1 team: 1973, 1975) a silver (C-1: 1973) and four bronzes (C-1: 1977; C-1 team: 1971, 1977, 1979).