Olga Thinn (12 June 1858 in Drammen – 6 January 1943 at Vinderen, Oslo), née Olga Wegner, was a Norwegian humanitarian and women's rights leader.

She was married to Chief Justice of the Supreme Court Karenus Kristofer Thinn.

She was a daughter of the judge Johan Ludwig Wegner and Blanca Bretteville, and a granddaughter of the industrialist Benjamin Wegner and of Prime Minister Christian Zetlitz Bretteville.

When living in Tromsø, she founded the local Women's Public Health Association there.

She was an honorary member of the Norwegian National Women's Council and received the King's Medal of Merit in Gold.