Announced at CES 2015 by Mad Catz is the Lynx Mobile Hybrid controller pictured above. It folds into itself for compact on the go travel gaming as well. I didn't get a chance to try it (so much to see), but Mad Catz is a known veteran in this gaming space and their last controller I tried gets close to 5 stars on Amazon (Mad Catz Mobile Gamepad.)

Update on 2015-01-12 04:35 by Mike Mu

Key features:

Connects via bluetooth
Main controller with removable left and right arms
Fits phablets
Two removable inner handles to improve grip
Comes with tablet stand controller frame to work with the larger tablets
MHL and HDMI adapter cables included
Also includes Keyboard module pictured
Works with PC, Mac, Android, iOS
Lasts 20-30 hours per charge, charges via microUSB (I believe)
33 feet range (standard bluetooth)