He's the least/most popular Star Wars character you've just got to love!
Right about now you are going, "Whoh there mister crazy guy, I watched all the Star Wars movies ad nauseam and I don't recall anyone named after a yak". And right you are. You do not recall him. He is perhaps the lamest character in Star Wars episode VI (Return of the Jedi). Yakface is on camera for a miniscule amount of time, and doesn't really do anything interesting with his short-lived fame.
So why is this little bitch worthy of note? And why did I refer to him as the most popular, as sucky as he seems (and as much as that totally contradicts me saying he was least popular)? The answer lies in his action figure.
That's right, despite his being of no importance whatsoever to the Star Wars universe, an action figure of Yakface was released in the original Return of the Jedi action figure set. And you know what? Nobody wanted a damn Yakface. They sold horribly, and over the years, became hard to find (I imagine many kids melted them into more interesting forms of entertainment, rather than live with the embarrasment of owning one). And now, with the resurgence of Star Wars addiction, and the new movies, the old action figures have become far more valuable. And Yakface is one of the most saught-after, as he has become so damned hard to find.
In addition, he's also a bit of a cult icon to super-nerds. How can you not love it when a sure loser rises to the top of the heap?
Gaze upon the visage of Yakface himself!
http://collectibles.echostation.com/toyguide/Vintage/actionfigures/Yak_Face/index.htm