The cult-classic Back to the Future II introduced us to 2015 versions of all the actors, and while the fashions and gadgets were, sadly, a little off (where's my hoverboard damn it?!) the aged actors themselves were almost spot-on.
It can't have been easy turning twenty-somethings into 40 to 50 year olds. Short of a bit of colour in his hair and a smidgen of weight, they got Michael J Fox dead-on. In fact, they were even closer with Thomas Wilson who's better known as Biff. Amazing, really, when you think about it back in 1989. [Reddit 1, 2 via io9]