Mario Jerrel Williams (born January 31, 1985 in Richlands, North Carolina) is an American football defensive end for the Houston Texans of the National Football League. He was selected first overall by the Texans in the 2006 NFL Draft, being the first player in Atlantic Coast Conference history to be chosen as the first overall pick. He played college football at North Carolina State University.

While playing in the ACC for North Carolina State under coach Chuck Amato, Williams played the defensive end position. He was a "blue chip" recruit coming out of Richlands High School, and he did not disappoint, starting at DE all three seasons. He recorded 175 tackles and 25.5 sacks in his 36 game career. In 2005, he was named to SI.com's All-American team and also to the All-ACC first team.

During the 2005 season, he started 12 games, recording 62 total tackles with 24 tackles for loss, 14.5 sacks, 15 hurries, a safety and a blocked kick. He maintained a 3.68 grade point average and according to reports, he would often be seen studying in the library on Friday and Saturday nights.