"Friherre" Major General Claes Fredrik Hugo Raab (25 November 1831 – 11 December 1881) was a Swedish Army officer. Raab fought in the Second Schleswig War as a volunteer and later in his career became the first Chief of the General Staff. With his international outlook, his concrete experience of the everyday life of the war and his great work capacity, Raab was one of the Swedish Army's foremost officers during the 19th century. He contributed actively to lifting the army out of its difficult recession in the 1860s and initiated the modernization of higher staff functions, officer training and organization which in 1885 would result in a decisive decision on an extension of the conscription defence and rounded off with the replacement of the Allotment system with a conscription-based defence in 1901.