Johansson, who is back for her fourth time, will kick off the first of the last new episodes of the season on May 2. Her musical guest will be Whiz Khalifa, making his SNL debut. Johansson's Avengers: Age of Ultron opens that week as well.
This month's InStyle cover girl Witherspoon, who has been everywhere lately promoting her May film Hot Pursuit with Sofia Vergara, will take on hosting duties on the May 9 episode. Her musical guest will be Florence + The Machine.
And last but not least, Louis C.K. will bring it home in the season finale. He's already hosted twice so we've got faith. Plus, if all else fails, he has Rihanna as his musical guest.