The canonical Igor of pop-culture is Dr. Frankenstein’s hunchbacked assistant — who does not exist in the original novel, and who isn’t named Igor in the movie:
Dwight Frye’s hunch-backed lab assistant in the first film of the Frankenstein series (1931) is the main source for the “Igor” of public imagination, though this character was actually named “Fritz”. The sequels Son of Frankenstein (1939) and The Ghost of Frankenstein (1942) featured a character named “Ygor”, played by Bela Lugosi; this character, however, is neither a hunchback nor a lab assistant, but an insane blacksmith with a broken neck and twisted back. He reanimates the Monster as an instrument of vengeance against the townspeople who attempted to hang him for graverobbing. He survives a near-fatal gunshot and appears in the next film, in which his brain is placed in the Monster’s body.
Universal Pictures would actively cement the idea of the hunchbacked assistant to the “mad scientist ” in the Frankenstein film series House of Frankenstein (1944) with J. Carrol Naish playing a hunch backed lab assistant named Daniel.
In the 1933 horror film Mystery of the Wax Museum, “Ivan Igor” is the name of the mad wax museum curator. The film was remade as House of Wax in 1953, but the name “Igor” was given to the curator’s henchman (played by a young Charles Bronson) rather than the curator himself. Not a hunchback, the character is deaf and mute, and is portrayed as an unconditionally devoted servant.
The name Igor, by the way, derives from the Norse name Ingvar, that was brought to ancient Rus by the Norse Varangians. Igor (son of the Varangian chief Rurik) conquered Kiev.