The Gadfly (Russian: Овод, romanized: Ovod) is a 1955 Soviet historical action film based on the novel by Ethel Lilian Voynich and directed by Aleksandr Faintsimmer. In 1955 the film was third in attendance in the Soviet Union, collecting 39.16 million ticket sales.

The motion picture tells a story of the underground struggle of Italian patriots against the Austrian invaders for independence of their homeland. Against the background of these events is a tragic story of a man transformed from a pure heart and an enthusiastic young man to a ruthless revolutionary—the legendary and elusive Gadfly.

The film adaptation is more ideological than the Voynich novel. The romantic subplot was significantly reduced; Arthur and Gemma are shown not as lovers but as party comrades and the jealousy between Arthur and Giovanni due to Gemma is not depicted.