The general public assumes something about a famous work that isn't true.
Sometimes a work will become so famous that even people who haven't read/seen/etc. it will still have some awareness of the work. Naturally, when people judge a work's content based on hearsay, there are going to be some misunderstandings. Sometimes those misunderstandings are just minor misquotations or other relatively mild things, but sometimes the misunderstanding of the work is so major that the public gets the completely wrong idea about the work's contents. Aesops get reversed, heroes turn into Ron the Death Eater and villains get mistaken for heroes. The misunderstanding must be both a popular one and a major departure from the work's intent for it to be an Uncle Tom Fallacy. As a rule of thumb, if more people believe a falsehood about a work is true than know the actual truth about the work, it's this trope. This will really drive fans of the work in question up the wall. When applied to a main character's name rather than the work's plot or message, it's I Am Not Shazam. [[folder:Literature]]