Carl Jahnzon (Carl Johan Jahnzon; 29 April 1881 - 25 June 1955) was a Swedish track and field athlete who competed in the 1912 Summer Olympics. In 1912 he finished eighth in the hammer throw competition.[1]
Jahnzon represented Djurgårdens IF.[1] Jahnzon also played football and played the 1904 Svenska Mästerskapet Final with Djurgårdens IF Fotboll, which his team lost to Örgryte IS.[2]