I know that I've used characters from movies and such as inspiration for the physical appearance of maybe a tiny handful of my own characters, but...never really went out of my way to base someone's appearance off of someone who exists in our world. I also never base my characters off of people I actually know. I want my stories to take me as far away from my real life as possible, after all. (That's why I write fantasy and sci-fi and avoid stories that are set in modern day settings.)
One of the fun things to do, however, AFTER you've written your story, is play the game "I'm making a movie of my book. Who would I get to play my characters?" If you haven't based your characters on actors, this is really hard to do. Nobody is really perfect for the roles, are they? But it's fun.
I've seen readers do this too - it's usually referred to as fancasting and it's super fun. Though I did have someone once fancast my character Nate with an actor that not only can I not stand, but bears zero resemblance to how he's described in the book. That was less fun, but as long as it made her happy I guess I did my job.
I'd like to think I don't. But then I've got a Talking Toilet and an UK Asian Buffy The Vampire Slayer who just looks like a UK Asian 17/18 year old still living at home. I've drawn my Talking Toilet and it's shower head of a Mother and even my two human characters, but the only people I want to change are my two human characters, the Toilet and the Mother I already have, and that's fine by me. ... That said, I did come here with a story idea of, UK being rebuilt as an American state, and I did have a Heroine like the one out of 28 Days Later (2002) later in mind and a Hero who gets killed off being from a position of power, and having him well dressed and have a villain who's greedy and 'in it for all the wrong/selfish reasons' who ultimately wins, and base him on someone the same age as the Hero and the Heroine, but almost be like an Anti Christ sort of History Channel Nostradamus Effect to play a politician anti Christ character, so a clean cut person to fear, but just make that the villain, and keep it all political. So, 28 Days Later Heroine faces off against a Anti Christ type business owner and UK ends up looking like America. Or better yet... Go casting in Camden for my Heroine.
