Thor-Øistein Endsjø (born 1 May 1936) is a Norwegian physician and former sports shooter.
He competed in the 25 metre pistol event at the 1972 Summer Olympics.
As a physician he worked at private clinics in Oslo and Bærum, include Humana which he co-established in Sandvika.
He has been the team physician for Norway in five Olympic Games and been associated with the Norwegian Athletics Association and several other sports federations.