Gunnar Olof Hyltén-Cavallius (1818–1889) was a Swedish scholar of cultural history, librarian, theatre director, and diplomat. Gunnar was the son of a clergyman from Vislanda, Småland, and the brother of the chemist Carl Erengisle Hyltén-Cavallius. While he was a student at the Uppsala University, he was impressed with the late currents of Gothicismus. He was an employee at the Swedish Royal Library in the period 1839–1856, the director of the Royal Theatres, 1856–1860, and the Chargé d'affaires in Empire of Brazil, 1860–1864.