Gösta Theselius (June 9, 1922 in Stockholm – January 24, 1976 in Stockholm) was a Swedish arranger, composer, film scorer, pianist, and saxophonist. His brother was musician Hans Theselius.

Theselius worked in the 1940s with a number of European big bands, including those of Thore Jederby, Hakan von Eichwald, Sam Samson, Lulle Elboj, and Thore Ehrling.^[1] He played jazz into the 1950s, both as a saxophonist and a pianist (on the latter instrument with Benny Bailey, Arne Domnerus, James Moody, and Charlie Parker), and composed copiously for film in the 1950s and 1960s.

• 1942 – Olycksfågeln nr 13
• 1951 – Uppdrag i Korea
• 1955 – Flicka i kasern
• 1955 – Paradise
• 1956 – Suss gott
• 1956 – The Stranger from the Sky
• 1956 – Flamman
• 1956 – Blånande hav
• 1957 – The Halo Is Slipping
• 1957 – Räkna med bråk
• 1960 – Kärlekens decimaler
• 1961 – Karneval
• 1961 – Två levande och en död