Marcelius Haga (29 September 1882 – 2 December 1968) was a Norwegian politician. Born in Høyland, he graduated from the Stord Teacher's College in 1902. He then worked as a teacher for four years before enrolling at the Norwegian College of Agriculture. He graduated there in 1908, and worked as a research fellow the following year. He then worked as a school teacher and manager as well as farmer the rest of his professional life, including two years at the Teacher's College at Notodden (today a part of Telemark University College).