Leonardo DiCaprio [1] celebrates his 40th birthday this week, which got us thinking about how many years he's been on the Hollywood scene. We still remember when Growing Pains welcomed DiCaprio into the family as Luke — because he stole our hearts pretty much immediately. It only got better from there, as DiCaprio charmed us in movies like Romeo + Juliet, Catch Me If You Can, and, of course, Titanic [2], all the way to The Great Gatsby. Take a look at some of his most memorable roles.