American professional gridiron football (football, gridiron) player who emerged as one of the leading quarterbacks in the National Football League (NFL) in the early 21st century.

Romo spent most of his childhood in southern Wisconsin, where he idolized Green Bay Packers quarterback Brett Favre (Favre, Brett), whose aggressive, risk-taking style of play he eventually sought to emulate. Although Romo was a standout player for Burlington (Wis.) High School, he was not recruited by the major college football teams and wound up attending Eastern Illinois University, a Division I-AA school in Charleston, Ill. At Eastern Illinois he was a three-time (2000–02) Ohio Valley Conference Player of the Year, and in his senior season he received the Walter Payton (Payton, Walter) Award as Division I-AA's top offensive player.

Despite being eligible for the 2003 NFL draft, Romo was again overlooked. Later that year he signed with the Dallas Cowboys as an undrafted free agent, but he earned little playing time in his first three seasons. He did not take over as starting quarterback until 2006, when he replaced an aging Drew Bledsoe near midseason. Romo blossomed almost immediately in the starter's role, helping the Cowboys land a wild-card spot in the playoffs. His ability to improvise plays and his willingness to throw downfield quickly made him a fan favourite. He finished the season having passed for 19 touchdowns and 2,903 yards and became the first Cowboys quarterback to be selected for the Pro Bowl since Troy Aikman in 1996.

Although Romo was blamed for the Cowboys' 2006 play-off loss to the Seattle Seahawks—he dropped the snap on a potentially game-winning field-goal attempt—he returned to lead the team to a 12–1 start in 2007, the best in franchise history. He threw for more than 300 yards in four of the first five games of the season as the Cowboys went on to win their first National Football Conference (NFC) East Division title in nine years. Romo finished the regular season with 36 touchdowns and 4,211 passing yards—another franchise record. In December he was again chosen for the Pro Bowl.