Licensing of popular TV shows, movies and books has been fairly common place throughout the hobby for as long as I can remember. In my post on MERP I only covered the RPG licensing of the setting for The Hobbit and The Lord Of The Rings.
Currently Middle Earth can be explored in a variety of forms whether that be wargaming with Games Workshop, collectable miniatures with Wizkids or any number of board and card games that are set in the world created by JRR Tolkien. And that's just what's currently being published!
Star Wars is another regularly used license with Fantasy Flight Games releasing a RPG, Card Game and in the form of X-Wing a Board/War Game (I can't decide). The key omission here is the lack of a full scale wargame along the lines of Warhammer. I'm not sure why this is the case as I can't think of any reason why any gamer (including this one) wouldn't be interested in playing the Hoth battle using miniatures...
Superheroes (primarily DC Comics and Marvel Comics) have also had a number of instances in the hobby with Heroclix being the main example but RPGs and Board/Card Games also exist. Plus to make sure no-one forgets there's an Atomic Robo RPG coming out!
Licenses for TV Shows have gone through a bit of a glut over the years with Firefly / Serenity, Stargate, Leverage, Supernatural, Smallville, Primeval and Dr Who all having RPGs. Some have multiple formats of games.
Now, none of this is bad as in many respects a product based on a licensed property increases the exposure of the hobby as a whole. It's also fair to say that a number of licensed products are one-shot publications to maximise the opportunity to tie-in with the popularity of the TV shows involved. Not saying it's a bad thing as afterall these are companies in the business of making money.
What am I saying then? A licensed game doesn't make it a good game. It doesn't provide any form of guarantee that the game will invoke the sensation of taking part in that license.
So by picking up a license, any license, a company gives themselves a good start in finding a player base for that game but at the same time that game better be good! The thing that kills a licensed product quickly is when the players buy it in droves but find that it's actually "not that good".
What games based on licenses were you most disappointed with?