When Peter Hall posted news yesterday (complete with photos) about rapper Curtis "50 Cent" Jackson losing 54 pounds off his chiseled physique to play a football player who gets cancer in Things Fall Apart, it got us thinking about other radical transformations actors have undergone for roles. Like Peter mentions, losing weight or altering your appearance for a part doesn't guarantee a great performance, but it does certainly show how dedicated an actor is to their craft. So, with that in mind, here are some of the greatest onscreen transformations in movie history. It has become more common in recent years for actors to show this level of commitment to a role, but I've chosen the ones that stand out as the most amazing to me. When you're done reading about my picks, I hope you'll head to the comments section and share some of your own favorite "performance-inspired makeovers."
You can't do a list of actor transformations without discussing Robert DeNiro in Raging Bull. The actor won an Oscar for his portrayal of boxer Jake LaMotta, and he packed on sixty pounds for the part. This was the first time a performer had really gone out of his way to change his physical appearance for a role, and the fact that DeNiro received acting's ultimate prize for his efforts almost certainly paved the way for other thespians to give it a shot as well. Raging Bull wasn't DeNiro's only extreme makeover for a part, though -- the actor repeated his weight-gaining regimen to play Al Capone in The Untouchables and went in the opposite direction, becoming a buff psychopath (who also reportedly ground his teeth ... ) in the remake of Cape Fear. Clearly, DeNiro takes the whole method acting thing seriously.

While some actors merely pack on the pounds for a good part (which, admittedly, doesn't sound like a bad part of the job ... ) others get bigger in a different way. In recent years, we've seen actors bulk up for parts, adding muscle mass and size in order to make their portrayals more convincing. Linda Hamilton got lots of praise for her ripped physique in James Cameron's Terminator 2 -- and rightfully so -- because it was a drastic transformation from her softer, more feminine, appearance in the first film. Yet, as impressive as Hamilton's transformation was, I can't help but think Edward Norton's decision to get ripped and shave his head for American History X is even more amazing. The actor put on roughly thirty pounds of muscle to play the skinhead in the film, something he achieved through intense workouts and a very specific diet. Norton's physical changes were so striking that men wanted to get on the same program -- which led to AskMen.com publishing an article highlighting the eating and training regimen you'd need to follow to look this buff.

Actress Hilary Swank is no stranger to altering her appearance for roles, having done it for both Boys Don't Cry and Million Dollar Baby -- and having taken home Oscar gold for both performances. In Boys Don't Cry, Swank chops off her hair and turns herself into a pretty convincing boy to recreate the real-life story of transgendered teen Brandon Teena. For Million Dollar Baby, the actress had to not only learn how to box, but bulk up so that she'd be believable in the ring. To achieve this, Swank reportedly spent two-and-a-half hours a day boxing, followed by another two hours of lifting weights -- six days a week. The end result was a gain of 19 pounds of muscle, which wound up grafted onto her slight frame. I'm sure it was a lot of hard work, but I'm guessing the Oscar made it all worthwhile.

Actors are, generally speaking, beautiful people. They spend a lot of time and money to look good -- so there are few transformations more shocking than when we see someone we generally think of as attractive show up onscreen looking like a complete wreck. Charlize Theron pulled this off for her portrayal of real-life serial killer Aileen Wournos in Monster. Theron gained thirty pounds and scuzzed up her hair/features for the part, which won her a Best Actress Oscar. It's shocking to see the normally beautiful Theron looking so rough and deranged. Meanwhile, Ellen Burstyn pulled off a similar makeover for her part in Darren Aronofsky's Requiem for a Dream. Burstyn makes herself look gaunt and rundown for her portrayal of a woman who's addicted to drugs as a dietary supplement. Burstyn and Theron both look absolutely horrible in these films, which is probably the greatest praise I can give them.

All of the movie role makeovers I've mentioned are shocking, but whenever this topic comes up now, there's one transformation that everyone thinks of -- Christian Bale in The Machinist. To play the part of a delusional insomniac, Bale dropped from 185 pounds to a freaky looking 121 in the span of three short months. To achieve this skin-and-bones appearance, Bale lived on coffee, water, an apple, and a can of tuna each and every day -- and nothing else. The end result is amazing, as the actor who was so physically stunning in American Psycho shows up in this film looking like he'd spent years in a concentration camp. Even more astounding is that the actor would then turn around almost immediately put 100 pounds of weight back on to appear in Batman Begins. Talk about yo-yo dieting ...

These are just the tip of the iceberg when it comes to celebrities transforming themselves to better fit a part. I can think of tons of examples that could have appeared on my list, but this is a discussion post, which means I'm turning the floor (and the comments section) over to you, the reader. Scroll down and share your thoughts below.