On real people who play characters with their names

Last night I was listening to an interview with Rob Corddry on "The Sound of Young America" on NPR, in which he spoke of the strangeness of the experience of playing a character that has your name. This was not the only time last night we referred to this phenomenon. In the 60 Minutes retrospective on the Obama campaign, Michelle Obama alluded to there being two people -- Barack Obama, the person she knew, and "Barack Obama" -- the phenomenon. Just as there was "Rob Corddry" the Judd Apatow-style resident asshole on The Daily Show, and then there's the smart, thoughtful guy who appeared in the interview.

Perhaps the most obvious example of a person playing a character that bears his name is Stephen Colbert. If you ever want to feel cognitive dissonance in action, imagine that you are a devout Catholic in the Montclair, NJ area and Stephen Colbert is your kids' Sunday School teacher -- which is in fact what he is on Sundays, when he is not "Stephen Colbert."

So what are these alter-egos that bear the names of real people? Is this a way for people to play roles the can't play in real life? Is it a manifestation of the id for which these people get paid handsomely? Is it just that these people have been fortunate enough to be able to present a public face that is the person they would really like to be, but aren't? And how do you get a gig like that?