Mark Ruffalo has been in the spotlight for almost three decades now, but he still makes us weak in the knees. We fell head over heels for him in romantic comedies like 13 Going on 30 and Just Like Heaven, we were eerily turned on by him in Leonardo DiCaprio's Shutter Island, and we still seem to lose our cool over his smoldering hot Hulk scenes in Marvel movies. What can we say? Mark is truly one of those actors who gets better with age. Whether he's shirtless, clean-shaven, or sporting salt-and-pepper hair, you will no doubt get a kick out of his sexiest photos.