The one that's always easy pickings - Boba Fett is the pseudonym of a man named Jaster Mereel who left his life as basically-a-cop to become a bounty hunter. Until Episode II comes out and Boba Fett is a clone of a Mandalorian named Jango Fett and who is this Jaster Mereel fellow, never heard of him. Until more works come out where Jaster Mereel was Jango Fett's father, no his mentor, no Mandalore, no Jango isn't a Mandalorian anymore, and so on and so on.
This is a franchise that had at least five levels of canon, despite being run by a single man. That is definitely unique among franchises, but in the opposite direction. It was a ridiculous mess.
ETA: The author of that story has a fantastic take on it all:Originally Posted by Daniel Keys Moran