Igor is a stock character in adaptations of the book Frankenstein by Mary Shelley. Normally, he’s a hunchbacked sidekick to either Victor Frankenstein or another mad scientist.
In the book, Frankenstein, Victor Frankenstein works alone when he creates Frankenstein’s monster and then abandons him. After that Victor has a nervous breakdown and starts to have hallucinations of the Monster and to suffer from “delirium” so Victor’s friend Henry Clerval takes care of Victor when Victor can’t take care of himself and nurses him back to health. But Clerval had nothing to do with creating Frankenstein’s monster and didn’t know that The Monster existed until The Monster killed him to get revenge against Victor.
In the 1823 play Presumption or the Fate of Frankenstein, Henry Clerval is worried about Victor Frankenstein’s mental health so he pays Fritz, Victor’s servant to tell him what is going on and Fritz tells Clerval that Victor is creating Frankenstein’s monster.
Fritz doesn’t appear in Thomas Edison’s movie Frankenstein (1910).
Fritz is in the 1931 movie Frankenstein made by Universal Studios. In it, Victor Frankenstein, renamed Henry Frankenstein, sends Fritz to steal a healthy brain from his professor but Fritz accidentally damages it so he instead steals the brain of a dead criminal. When the Monster is scared by sunlight, Henry and Fritz lock him in a dungeon where Fritz scares the Monster by using fire so the Monster kills Fritz by strangling him to death.
In the movie Bride of Frankenstein, Dwight Fyre, who played Fritz, plays a man named Karl who is the sidekick to an evil mad scientist named Dr. Pretorius.
In the movie Son of Frankenstein, Bela Lugosi plays a shepherd named Ygor who has a broken neck from when he was hanged but survived. And when Wolf Frankenstein brings The Monster back to life, the Monster only listens to what Ygor says. Ygor uses the Monster to kill the people on the jury that sentenced him to death for grave robbery and frames Wolf. So Wolf shoots Ygor.
In the sequel Ghost of Frankenstein, it turns out that Ygor is alive and wants to get revenge.
In the movie, House of Frankenstein, the mad scientist, Dr. Niemann has a hunchbacked sidekick named Daniel.
In the movie Young Frankenstein, Dr. Frederick Frankenstein, whose grandfather was Victor Frankenstein gets an assistant named Igor, who says his name is actually pronounced Eye-Gore, and whose grandfather worked for Victor Frankenstein. Igor has a hump on his back.
In the Discworld books by Terry Pratchett, every mad scientist has a hunchbacked sidekick named Igor and all Igors are actually related to each other. Every man in their family is named Igor and every woman is named Igorina. They all lisp when they speak.
The 2008 animated movie, Igor starring John Cusack is set in a world where every mad scientist has a hunchbacked sidekick named Igor.