Cort Sivertsen Adeler (16 December 1622 – 5 November 1675), known in Denmark as Coort Sifvertsen Adelaer, in The Netherlands as Koert Sievertsen Adelaer and in Italy as Curzio Suffrido Adelborst, was the name of honour given to Kurt Sivertsen, a Norwegian seaman, who rendered distinguished service to the Danish and Dutch navies, and also to the Republic of Venice against the Turks.