4. Koyi Mateil
What you see in the films: In Episode III, Palpatine has Anakin Skywalker meet him at a theater, where we see a luminous show of organic light of some kind. What we also see are people filing out of the building on a red carpet at the end of the show, one of which is the scantily clad Twi'lek female Koyi Mateil.
The expanded backstory: The show Mateil and the others attended was the premiere performance of Squid Lake at Coruscant's Galaxies Opera House. Hailing from the planet Ryloth, Koyi was a socialite who married Duke Teta for his money, and secretly hopes he will soon die so she can inherit his fortune. She artificially colored her skin to appear more human, presumably to be sexually attractive. Mateil's backstory isn't necessarily convoluted, but it's a testament to how deep a world is created for characters who appear on film for a split second in the background (in a very wide shot). This is just one of many show-goers who is exiting the building, and we now know all about her sham of a marriage and her grooming tendencies.