Ulf Torbjörn Harald Tännsjö (Swedish pronunciation: [ˈtǔːrbjœɳ ˈtɛ̂nːɧøː]; born 13 December 1946 in Västerås) is a Swedish professor of philosophy and public intellectual. He has held a chair in Practical Philosophy at Stockholm University since 2002 and he is Affiliated Professor of Medical Ethics at Karolinska Institute. Tännsjö was Associate Professor of Philosophy at Stockholm University from 1976 to 1993 and Research Fellow in Political Philosophy at the Swedish Research Council in the Humanities and Social Sciences between 1993 and 1995. Thereafter, he was a professor of Practical Philosophy at Göteborg University 1995-2001.