The fashion & beauty icon who had a big influence on me is Marilyn. It also happens to be the person I have read most about, though it was an easy task seeing that she must be one of the most written about people.
Lucky enough my favourite one, which also happened to become one of my favorite books is one of her french biography (sorry). But it was concise, interesting and fast.
Whether you already know quite a lot about her or is your want to "get to know her", this book is very good.
But watch out, you might end up liking her just as much as I do.