Matthew Leinart (born May 11, 1983 in Santa Ana, California) is an American football quarterback (QB) for the Arizona Cardinals. He played college football for the University of Southern California Trojans, leading them to two national titles. Leinart earlier played QB at Mater Dei High School, Santa Ana. In 2004, his junior year at USC, he won the Heisman Trophy. He also won the inaugural Manning Award for college quarterbacks in the same season. Anticipating his entry into the NFL, he signed with Creative Artists Agency to handle endorsements, and Leigh Steinberg to be his agent in January 2006 (although Leinart fired Steinberg three months later).

In his redshirt freshman year, he backed up then-quarterback Carson Palmer, who also won the Heisman and is currently the starting quarterback for the Cincinnati Bengals. In the following offseason, Leinart beat out Matt Cassel and former Purdue transfer Brandon Hance for the Trojan starting job at QB. After taking over as USC's starter, Leinart accumulated a 37-2 record, was named Pac-10 Offensive Player of the Year twice, and won the prestigious Heisman Trophy. Leinart is the all-time Pac-10 conference leader in touchdowns with 98. Leinart passed Palmer in 2005 as USC's all-time passing leader, and was one of only five players to go into a season with the possibilty of winning two Heisman Trophies, joining Archie Griffin in 1975, Billy Sims in 1978, Ty Detmer in 1991, and Jason White in 2004; Leinart joined Sims, Detmer, and White in failing to do so.

On December 7, 2005, Leinart was selected as a Heisman Trophy finalist for a second consecutive year, set to appear again at the award ceremony in New York City with teammate Reggie Bush and University of Texas at Austin quarterback Vince Young. Having won the Heisman Trophy in 2004, he was able to cast a vote for the 2005 Heisman; Leinart voted for Bush over himself, and Bush went on to win the Heisman by the 17th-largest point margin in the award's history. After numerous accolades and 34 straight wins as a starter, Leinart's college career ended on a slightly sour note as he and his USC Trojans fell to Young and the Texas Longhorns in the 2006 Rose Bowl, 41-38. Leinart himself had a typically spectacular game, completing 29 of 40 passes for 365 yards, one interception, and a touchdown against a Longhorn defense that was statistically among the best in the country, but his performance was overshadowed by Young's own sensational effort in leading Texas to the victory. In a postgame interview, Leinart said that despite the Trojans' loss to Texas, "I still think we're a better team. They just made the plays in the end."

By returning to USC for his senior season in 2005, Leinart probably hurt his draft position, as he most likely would have been selected with the first overall pick of the 2005 NFL Draft (and would've likely ended up with the San Francisco 49ers). Instead, Leinart was selected tenth overall in the 2006 Draft by the Arizona Cardinals, where he will likely be mentored by former NFL MVP quarterback Kurt Warner. Leinart will wear jersey #7.

While he was taken lower than many experts predicted, he was still the second quarterback selected in the draft (Texas' Vince Young was taken third overall), and during the draft's television coverage, ESPN commentators noted that star quarterbacks such as Dan Marino and Ben Roethlisberger also fell in the draft before forging very successful careers.