Karin Maj Britt Margareta Theorin (born December 22, 1932, Göteborg), commonly known as Maj Britt Theorin, is a Swedish social democratic politician and diplomat. She served as a member of the Parliament of Sweden from 1971 to 1995, and as a Member of the European Parliament from 1995 to 2004. She was President of the International Peace Bureau from 1992 to 2000, following Bruce Kent. She has also served as Swedish Ambassador for Disarmament.
As an MP in the 1980s, she proposed that private ownership of satellite dishes be prohibited in Sweden. The intention was to stop Swedish citizen from watching commercial television channels from abroad and thus preserve the Swedish state television media monopoly.