Williams has been a member of the Seattle Seahawks, New England Patriots, Buffalo Bills, Carolina Panthers, and Tampa Bay Buccaneers.

[1] Thomas R. Williams entered USC in the 2003 recruiting class that included Reggie Bush and LenDale White.

[2] Williams started 14 games at 3 different positions (including fullback) while playing college football at USC.

During his time with the Trojans, Williams received guidance and feedback from veteran linebackers such as Lofa Tatupu, Matt Grootegoed, Dallas Sartz, Collin Ashton, and Oscar Lua.

[1] During his redshirt freshman year he was an active member of the 2004 National Championship team, where he played behind Sartz at the strong-side spot.

[2] Early in the 2004 season, Williams was nicknamed "The Hitman" by coach Pete Carroll for his performance on special teams; the name stuck with him for his career at USC.

[2] During the 2006 season, when the Trojans fullbacks were decimated by injury, members of the offense such as Ryan Kalil, Sam Baker, and John David Booty, asked him to switch positions to fullback, a position he had played in high school.

He was promoted to the Patriots' active roster on January 6, 2010, in advance of their playoff game against the Baltimore Ravens, for which he was inactive.

Williams was signed to the Buffalo Bills practice squad on October 12, 2010 and later added to the active roster.