It is certainly possible to alter the facial appearance of a person to make him/her resemble another person using [prosthetic make-up][1].

But those shown in the movies such as Mission Impossible, Charlie's Angels and the one depicted above are not practically possible as it would involve the mask to be a *one-piece* wearable and removable item, very much unlike current date prosthetic masks that are a *composition of a set of different pieces*.

To gain a little more perspective of what I am talking about you could go through [this][2] slide that shows the transformation of *Mr. Amitabh Bachchan* for the Bollywood movie *Paa*.


  [1]: http://www.themakeupgallery.info/lookalike/index.htm
  [2]: http://www.slideshare.net/rahul/amitabh-bachchans-makeup-in-paa