Mark Matthew Stepnoski (born January 20, 1967) is an American former professional football player who was an offensive lineman in the National Football League (NFL). He attended Cathedral Preparatory School in Erie, Pennsylvania, and went on to star at the University of Pittsburgh. He played 13 seasons in the NFL, with the Dallas Cowboys from 1989 to 1994, with the Houston / Tennessee Oilers from 1995 to 1998, and back to the Cowboys for three more seasons. Stepnoski won two Super Bowls with the Cowboys and was selected to five consecutive Pro Bowls from 1992 to 1996.

Stepnoski, was a highly recruited All-State and Parade All-American offensive tackle from Erie Cathedral Preparatory School. He graduated from the school in 1985.

He signed with the University of Pittsburgh and became a four-year starter at offensive guard, helping clear the way for Craig Heyward and Curvin Richards to become two of the leading rushers in the nation.

Stepnoski was a third-team All-American as a sophomore, a consensus first-team All-American in 1988 and a finalist for the Outland Trophy as a senior. He was a two-time Academic All-American (1986 and 1988). He also played in the East–West Shrine Game.

All values from NFL Combine

Stepnoski was selected by the Dallas Cowboys in the third round of the 1989 NFL draft. He dropped in the draft because the scouts thought he was undersized for the National Football League.

The Cowboys switched him to center, although he had never played that position. During his rookie year he was tutored by Tom Rafferty, who was playing his last season in the NFL. He became a starter for the last four games of the season. Stepnoski used his athletic ability, leverage and balance to outmaneuver bigger defensive players and become one of the league's best centers of his era. By the end of the 1991 season he was selected to the first of five straight Pro Bowls. From 1992 to 1994, together with Erik Williams, Mark Tuinei, Nate Newton and Kevin Gogan, he was part of some of the best offensive lines to play in NFL history, that also helped pave the way for Emmitt Smith to become the NFL's all-time leading rusher. In 1993, he suffered a knee injury that required surgery while playing against the Minnesota Vikings in the 13th game of the season. He was replaced by John Gesek and couldn't play during the playoffs and Super Bowl XXVIII. He became a free agent at the end of the season, but the Cowboys could only sign him to a one-year contract ($1.2 million and a $500,000 signing bonus).

Stepnoski was one of the team's first big-name players to leave the Cowboys following the 1994 season via unrestricted free agency, leaving with three Pro Bowls and back-to-back Super Bowl victories.