One half of one of the most famous Hollywood couples is stopping by -- KATIE HOLMES! She's now playing one of the most famous wives, Jackie Kennedy, in the controversial new mini-series, "The Kennedys" -- and she's here to tell Ellen all about it.

People can't get enough of KIM & KOURTNEY KARDASHIAN! The two are the queens of reality television and can hardly go anywhere without being swarmed by paparazzi. That's not stopping them from going to New York for their new show, "Kim & Kourtney Take New York" -- but today they're visiting Ellen first!

Whenever ONEREPUBLIC is here, they always give one of the best performances. Today they're back to sing their latest hit, "Good Life," from their album, "Waking Up."