William Markus, born Karl William Marcus, was a Finnish-British film director, actor, screenwriter, and producer. Born in Liverpool to a Finnish father and an English mother, he held dual citizenship in Finland and the United Kingdom. Markus began his acting career in 1944 and later transitioned into directing. He directed 13 films between 1953 and 1965, with notable works including Miriam (1957), which was entered into the 8th Berlin International Film Festival. His films often explored complex social themes, contributing significantly to Finnish cinema during his active years.

Hornankoski
1949 · as Aarne Yli-Koskela

Vain laulajapoikia
1951 · as Dr. Kaarlo Lehmus

Maaret – tunturien tyttö
1947 · as Rolf Brenner

All this - and Iceland too
1951

On lautalla pienoinen kahvila
1952 · as Vuoristo 'Eräs'

The Log Drivers
1953 · as Arne

Kenraalin morsian
1951 · as Olavi Naula

Rakas varkaani
1957 · as William Markus (uncredited)

Dynamiittityttö
1944 · as Esko Vuoristo

Matkailijan keitaita
1953

Suomalaistyttöjä Tukholmassa
1952 · as Sven

Hormoonit valloillaan
1948 · as konttoripäällikkö Kivi