Check out the "trailer" below for "Revenge of the Jedi," which was the title of Star Wars: Episode VI prior to Return of the Jedi.
According to reports, writer Lawrence Kasdan thought "Revenge of the Jedi" was too weak of a title, so eventually George Lucas changed it to Return of the Jedi.
In addition, it's said the Jedi aren't supposed to seek revenge, which is another reason for the change.
The marketing for "Revenge of the Jedi" even got so far as having thousands of posters released. Check out one below.