I'm not sure what to call Ken Wilber. Some sources refer to him simply as a writer. There's a biography of him at http://www.worldofkenwilber.com/ where you can read a little bit. (When I visited the biography page, I found it rather dated, but it gives you an idea of his beginnings.) There are a lot of other links to Wilber in Google.com.
His effect on me was to turn upside down my philosophy. "There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy." While these words from Hamlet were uttered in a different context, I've often recalled them in reviewing the changes in my own view of reality in the past few years. I didn't read his books in the order he wrote them, but began with the Eye of Spirit when it was published in 1997. Subsequently, I gorged myself on his writings. (By the time his Collected Works was published, I had read all but a couple of short pieces--I could have saved myself a lot of money by waiting and buying the Works.)
I don't know how I would recommend one begin reading Wilber. He has divided his books by major changes he himself has gone through: Wilber I, Wilber II, Wilber III, etc. In the introduction to Volume 1 of Collected Works, he describes these changes, and says that even though he moved past some of his ideas from his early books, they still hold value. And for me, they introduce one to a profound theory and a very complex structure through which one can view reality in a different way. If you read The Spectrum of Consciousness (1977) first, you get the very basis for most of his subsequent writings. By the time you get to A Brief History of Everything (1996), you might be less confused by that 330-page condensation of the much larger Sex, Ecology, Spirituality: The Spirit of Evolution, published the year before, if you've read the earlier works.
Not everybody is as enthusiastic about Ken Wilber as I am. His intelligence is phenomenal, but he doesn't offer a New Age solution to everybody's spiritual needs. Teachers connected with the Insight Meditation Society in Barre, Massachusetts and Spirit Rock Center in California have published a number of books to acquaint one with vipassana meditation and how one might pursue a path to the higher levels of consciousness that Wilber writes about. Before reading Wilber, however, I would not have opened one of those books, because even though I didn't know what Ultimate Reality might be, I was sure I wouldn't find out through mysticism.
There are, indeed, more things in heaven and earth than I had ever dreamt of.
Read a related essay, Levels of Consciousness