Karl Gunnar Alfred Karlsson-Tjörnebo (23 March 1927 – 15 March 2009) was a Swedish long-distance runner who specialized in the 3000 metres steeplechase.
He competed at the Olympic Games three times, with a twelfth place in 1952, a fifth place in 1960 and a failure to reach the final in 1956.
At home, he won six national championships between 1951 and 1961, and set four Swedish records in his main event.