Puzzle Master

As I'm going to sleep at night--a process that takes progressively more time as pregnancy continues--I like to listen to NPR. I like their science shows, the news quiz show, I like most of their "All Things Considered" and "Morning Edition" (I like mocking their left-ward slant), etc. On Sunday mornings, they have a little puzzle segment that you can try to figure out. If you do, and you get it right, and your entry is picked, you get all sorts of prizes and get to try some real live puzzles on the air.

So last night's (actually yesterday morning's) puzzle was DRIVING ME CRAZY, because I felt like I knew the answer. Here it is:

Name a famous male movie star. Change the first letter of his first name to a G and change the last letter of his last name to a T. The result will be two words that are synonyms. Who is the movie star and what are the words?

I finally figured it out! (I'm embarrassed to tell you what I resorted to or how long it took me, but I did not cheat or look online for the specific answer. I did use lists of famous actors from online, though...)

I'll give you a clue, if you are so inclined to try to figure it out. I know FOR CERTAIN that you all have heard of this actor. Hey, and if you figure it out, go ahead and submit your answer at the link above. Maybe you'll win!

My (presumed correct, because I am brilliant) answer is in the comments.