Five Great Sandbox/Free Roam Games

When Grand Theft Auto came about, it set a huge trend. After the arrival of GTA3 on the Playstation 2 there was a huge wave of sandbox titles; the genre became very popular. As someone who is highly appreciative of sandbox games myself, I decided to write up a list of five great sandbox games that I enjoy. Check it out and leave comments; It would be cool to see what you guys think also.