For this one, I'm going back to Day 3, and saying that one of my favorite protagonists is Melacha Rendell (aka Skyrider) from Melisa Michaels' Skyrider series.
At face value, Skyrider is a rather stereotypical seeming "tough guy" (nevermind that she's a girl) heroine. She's a daring pilot, a bit of a scoundrel and rather enjoys her reputation as a swashbuckling mercenary. But she has flaws, as well. She carries a lot of guilt under that tough exterior, both for her non-role in the Colonial War and the death of her lover in a shuttle malfunction. She tries to hide her feelings under a brash cover. She is as likely to start throwing punches as she is to buy a teddy bear as a present for a relative's child. And she has a soft spot for cute, blue-eyed six year olds, which leads her to the two people who manage to get under that tough hide. Oh, and sarcasm. Did I mention sarcasm? Yeah, something near and dear to my heart!
Again, these are not deep books, but they are really fun reads. And gave me a character I truly enjoy reading (and re-reading).