Here's an autographed Mortal Kombat II, complete for Sega Genesis, up for auction on ebay. It is signed by Daniel Pesina, who played Johnny Cage and all the ninjas (Scorpion, Reptile, Sub-Zero, etc.) in Mortal Kombat I & II. The auction gives more details about it. Personally, I've never seen any signed MK games on ebay, and my guess is that Pesina would be the most sought after signature of any MK actors or designers.
Side note, regarding autographed games... in the '90s, with the influx of FMV style games and developers using digitized actors in games (like MK did), there was a whole era of games where real actors were used in video games. Nowadays, there might be a few famous voice actors to sign a game (say, for example, David Hayter as Solid Snake), and certainly game designer signatures on marquee games are always a big deal.. but has there ever been a bigger in-game actor than Daniel Pesina in Mortal Kombat I & II? Probably, but can't think of one off the top of my head...
Anyway, here's the link:
http://www.ebay.com/itm/SIGNED-Morta.../322304170163?