Hans Bertil Mattias Gardell (born 10 August 1959) is a Swedish scholar of comparative religion. He is the current holder of the Nathan Söderblom Chair of Comparative Religion at Uppsala University, Sweden. He is also the first award winner of Jan Myrdals big prize in 2009, and received The Royal Swedish Academy of Letters, History and Antiquities Award for Distinguished Research in the Humanities, the Royal Gold Medal, in 2003.
Mattias Gardell was born in Solna, , Sweden. He is the son of Bertil Gardell, a professor in social psychology, and the brother of writer and comedian Jonas Gardell. He earned a Ph.D. in the history of religions at in 1995 and became a docent in 1999. He has been working at the Department of Comparative Religion and the Centre for Research in International Migration and Ethnic Relations at Stockholm University. He has also lived and studied in Cairo, Egypt. In March 2006 he was appointed the first holder (from 1 July 2006) of the Nathan Söderblom Chair of Comparative Religion at Uppsala University.
Gardell specializes in the study of religious extremism and religious racism in the United States, studying groups such as the Ku Klux Klan, Nation of Islam, and folkish movements in Neopaganism (Odinism). Ron McVan, who collaborated with Gardell for Gods of the Blood, states that he had "once sworn an oath of brotherhood to me in my Viking hof." Gardell is partly blamed by McVan for accusations of plagiarism.