Before Christian Bale became the buff version of himself for Batman in Christopher Nolan's 'Dark Knight' trilogy, he was at his slimmest for the lead role in 2004's 'The Machinist.' In it, he portrayed a man on the brink of insanity as a result of his year-long insomnia, and though he was not required to drop a ton of weight, Bale felt the role called for someone who physically appeared to be on the brink of death. He previously stated:

I lost about a third of my body weight and went down to about 121 pounds. I didn't really know how else to do it. I just thought my character should look as though he was on the brink of death, but I didn't set out to actually get as skinny as I did. I just found that I was somewhat more successful at it than I'd imagined.

The above left photo shows Bale a year before the 'Machinist' premiere.