Agent Smith is the best bad guy in The Matrix and one of the most iconic sci-fi movie villains ever, but he isn't always played by the same actor. Although Smith is in every Matrix movie, he gradually transforms as the series progresses. The character creates a common thread throughout the franchise and serves as the nemesis to Keanu Reeves' Thomas "Neo" Anderson and the other Matrix escapees. Not every actor who inherits the job adds something new to Agent Smith, as the man who originated the role did such a great job that he is often deemed worthy of imitation.

Agent Smith is a sentient computer program, otherwise known as a Program in The Matrix, but he eventually becomes a Virus. This category of characters is largely restricted to the digital world, but Smith goes far beyond being a traditional Program. Although Smith begins the saga as a loyal servant to the Matrix,...