Karl Otto Fazer (Finland Swedish pronunciation: [ˈkɑːrl ˈutːo ˈfat͡sær], 16 August 1866 – 9 October 1932) was a Finnish chocolatier and sport shooter.

Fazer studied baking in Berlin, Paris, and Saint Petersburg before becoming a pioneer of Finnish confectionery.

Fazer established bird protection areas in the Åland archipelago and on the lands of the Taubila farm he bought in 1918 in Pyhäjärvi, Vyborg County, Karelia.

Fazer died in 1932 at the age of 66 after suffering a heart attack on a hunting trip in Jokioinen.

Fazer was an excellent marksman who participated in the Olympic Games in 1912 with the Finnish shooting team.