Episode I: The Phantom Menace
For starters, Liam Neeson is one of my favorite actors. Despite its shortcomings, The Phantom Menace does have its strong points, and it was neat to see the relationship between him and a young Obi-Wan Kenobi as master and apprentice.
Plot wise it makes sense for him to die early on, but that doesn't make his impact any less important. Even from death his presence is known; he tries to stop Anakin during his slaughter of the Tuskens and eventually teaches Obi-Wan and Yoda how to come back as a Force Ghost.
One of the coolest Jedi that the Order has to offer, Qui-Gon Jinn slides in at #10.
R2-D2 continuously plays a huge role in the story of star wars, from saving main characters lives, to being the reason that the original trilogy ever happens, R2 is a huge player in star wars, and a loveable character as well. R2 transports the rebel plans to obi wan, which propells him and luke on the journey that becomes the amazing story of the original trilogy. Without R2 this probably would have never happened.
R2 is stubborn, but for a good reason, because he knows that he plays an important role in the rebels success in this war against the empire. Even though he doesn't really speak, he is witty as we see through C-3P0s translations.
R2 is one of starwars most memorable characters and a main reason everything happens. This is why he comes in at number 10.
You hardly see any of this IG-88 in the movies. In fact you only see him briefly in Empire. In my defense, you don't see another fan favorite I assure you will be much higher on my fellow MTN member's list, Boba Fett. So what makes me like him so much? The expanded universe. I almost cheated and put this one as all of the bounty hunters. While there is very little on them in the movies, the novels really flesh out their story.
One of my favorites is the story of IG-88. I don't remember if it was Tales From the Bounty Hunters or Tales From the Empire (pretty sure the former), there is a story about the bounty hunter robot where he ends up taking control of the Death Star 2. It really puts into perspective how devious and scheming he is. It's also mind blowing to think of this character as being in control of the most powerful weapon in the universe. Heck, he became the most powerful being in the universe.