Who? Don’t worry if that was your first reaction as even the most keen-eyed fan may have missed IG-88’s blink and you’ll miss it appearance in The Empire Strikes Back.
The assassin droid was beaten to Han Solo by Boba Fett and the two developed a serious rivalry as a result. Thanks to the “Expanded Universe” novels and comic books, the history and characteristics of IG-88 were considerably fleshed out, making him undeniably one of the most interesting villains in the franchise.
However, it could be argued that his appearance would be better saved for the planned Boba Fett spin-off, although a cameo of some sort may not be a bad way to remind fans that they shouldn’t underestimate this formidable and deadly android no matter how limited his time on screen was.