Isak Larsson Flatabø (11 September 1896 – 22 January 1969) was a Norwegian politician for the Labour Party.^[1]

He was born in Vikør Municipality. He was elected to the Norwegian Parliament from Hordaland in 1945, and was re-elected on four occasions. He had previously served as a deputy representative in the periods 1934–1936 and 1937–1945.^[1]

On the local level, Flatabø was a member of the municipal council of Kvam Municipality from 1927 to 1940. He chaired the local party chapter from 1933 to 1934, and the county chapter from 1953 to 1958.^[1]

Outside politics he worked as a manual laborer and as a farmer. He was active in the International Organisation of Good Templars.