Zach Galifianakis
You might be more familiar with his work on Between Two Ferns, or perhaps you know him from The Hangover trilogy. In any case, many people remember Zach Galifianakis as a big guy. When he quit drinking in 2014, however, he made an incredible 50-pound weight cut.
Jonah Hill
Jonah Hill definitely deserves all the praise he has been getting for shedding many pounds. If you know him from Superbad, it is possible you will not recognize him now.