Zachary Michael Thomas, born September 1, 1973 in Pampa, Texas, is a former American college and professional football player who was a linebacker in the National Football League for thirteen seasons. He played college football for Texas Tech University, and was recognized as a unanimous All-American. He was drafted by the Miami Dolphins in the fifth round of the 1996 NFL Draft, and played for the Dolphins his first twelve seasons in the NFL. He was selected to the Pro Bowl eight times and recorded over 1,700 tackles.

Thomas attended Texas Tech University, where he was a three-year starter at linebacker for the Texas Tech Red Raiders football team. As a junior in 1994, he was a first-team All-American. As a senior in 1995, he was a unanimous first-team All-American, the Southwest Conference Defensive Player of the Year, and a finalist for the Butkus Award. Thomas is one of 5 Red Raiders to be named a Unanimous All-American along with Mark Bounds, Byron Hanspard, Michael Crabtree, and Jace Amaro. He recorded 390 tackles, including a career-high 131 tackles and a school-record 20 tackles against Missouri in his senior season. During the 1995 game against Texas A&M, Thomas returned an interception to gain a 14–7 win for Tech. Thomas and his brother Bart were the only pair of brothers to be named first-team All-Southwest Conference selections in the same year.

Thomas was drafted in the fifth round of the 1996 NFL Draft. On July 3, 1996, Thomas agreed to a three-year $577,000 deal with Miami. He was a Pro Bowl alternate and an All-Rookie selection in 1996. In 1997 Thomas totaled 128 tackles while playing and starting 15 games. In 1998 Thomas made All-Pro for the first time, making 133 tackles, a sack, an interception and forcing a fumble as the Dolphins defense allowed the fewest points in the NFL.

Thomas led the Dolphins in tackles with 165 in 2005 after missing two games with ankle and shoulder injuries. He is also one of three players to record one hundred or more tackles in each of his first ten seasons in the NFL. Thomas was selected to his seventh Pro Bowl appearance in 2006, tied for the third most Pro Bowl appearances in club history; this is also the most of such selections among all defensive players in Dolphins history. He has also been selected First- and Second-Team All-Pro seven times.  Zach Thomas has more tackles than any linebacker in the Pro Football Hall of Fame, currently ranking sixth all-time. Thomas’ tenure with the Dolphins ended on February 14, 2008.

On February 23, 2008 after contract offers from the New Orleans Saints and New England Patriots, Thomas decided to sign in principle with the Dallas Cowboys to a one-year, $3 million contract. The deal included a $1 million base salary, a $1 million signing bonus and a $1 million incentive-based bonus based on playing time that agent Drew Rosenhaus said should be easily attained.

An unrestricted free agent in the 2009 offseason, Thomas agreed to terms with the Kansas City Chiefs on April 11, 2009. The one-year contract was worth $2 million. He was released at the end of the preseason after not playing in any exhibition games. On May 18, 2010 Thomas signed a one-day ceremonial contract, officially worth $1, in order to retire as a member of the Miami Dolphins.

Thomas is married to Maritza Thomas. Thomas has one son, Christian Zachary, and one daughter, Valentina.