The University of Oslo (Norwegian: Universitetet i Oslo, Latin: Universitas Osloensis) is the oldest and largest university in Norway. It is in the Norwegian capital, Oslo.

The university began in 1811 as The Royal Frederick University (in Norwegian Det Kongelige Frederiks Universitet and in Latin Universitas Regia Fredericiana). The university was modelled after the recently established University of Berlin, and originally named after King Frederick of Denmark and Norway. In 1939 it changed to the name it has now.

The university has faculties of (Lutheran) Theology, Law, Medicine, Humanities, Mathematics and Natural Sciences, Dentistry, Social Sciences, and Education. The Faculty of Law is still located at the old campus on Karl Johans gate, near the National Theatre, the Royal Palace, and the Parliament. Most of the other faculties are at a modern campus area called Blindern. The Faculty of Medicine is split between several university hospitals in the Oslo area.

In 2019, the university had 30,505 students and employed 6,595 people.^{[2][needs update]}