In a bit of startling news, 20th Century Fox Co-Chairman and CEO Tom Rothman will be leaving the studio.  In letter to Fox staff, Rothman says he will resign on January 1, 2013.  A source tells THR that all studio operations will be consolidated under studio co-chairman Jim Gianopulos.  It's a surprising departure considering Fox's recent good fortune at the box office with hits like X-Men: First Class, Rise of the Planet of the Apes, and Chronicle.  Rothman had been with Fox for over 18 years.Hit the jump to read his full letter, and click here to read Steve's interview with Rothman from CinemaCon.Here's a letter from Rothman to Fox employees [via THR]:

My Dear Friends,

I have decided that, after more than 18 years -- the bulk of my adult working life -- I am resigning as Chairman and CEO of Fox Filmed Entertainment, effective January 1, 2013.  During my time at Fox, thanks to you, we have together accomplished more than I ever imagined possible, from the founding and nurturing of Searchlight, to overseeing the two biggest films in box office history, to consistently ranking at the top among studio profitability year in and year out (including our most recent strong fiscal year), and, most of all, making dozens of exceptional films that I believe will stand the test of time.  I’m proud as hell of that run.  But I’ve done the same thing, at the same place, for a long time (indeed, in the 75 year history of our studio, no one has supervised movies for longer except Darryl Zanuck himself).  I do need some new challenges and to write a new chapter.

I love Fox and all of you and take comfort knowing that, although there is never a perfect time to leave, because the slate for the next several years is in awesome shape, this is at least a pretty good one.  I know that Jim G. and all of you will continue our long tradition of winning ways, and I will be rooting hard for you.  I will also be around until the end of the year to help with the transition and celebrate some of the hits we are about to have.

Finally, let me say, how eternally grateful I will always be for the privilege and the honor of having had this job, and above all else, working with you all --  quite simply, the best, most talented, and the kindest colleagues in the world.  If I can leave you with one thought, it’s this:  for all these years, I have tried to do the job with, above all else, integrity.  I think our company stands for doing what is right, even if that is not always easy, and for prizing honesty and forthrightness.  I hope that you will carry that mission forward.  As for me, a bunch of you guys know what the tattoo on my ankle says.  It’s what I wish for us all:  “Excelsior”!

With Love and Gratitude,

Tom