Most Famous Hollywood Celebrities Stars Turning 40 in 2010

- Can you believe Matt Damon turns 40 on October 8? It seems like it was just yesterday when we saw Matt utter his first line of movie dialogue in 1988's "Mystic Pizza" at age 18. But we knew the cute Boston boy was destined for big things. Damon -- who is now happily married with two children (and a third on the way) -- nabbed a Best Original Screenplay Oscar for "Good Will Hunting" in 1997 and has starred in numerous movies including "The Talented Mr. Ripley," "The Bourne Identity" series, and "The Departed" to name a few.