Mark Prior, American baseball player
Mark William Prior (born September 7, 1980) is an American former professional baseball pitcher and current coach. A onetime top prospect of the Chicago Cubs, he pitched for the team from 2002 to 2006 in a career that was marred by injuries. In his prime, his repertoire of pitches included a mid-90s mph fastball, a curveball, and a changeup. He is currently the pitching coach for the Los Angeles Dodgers.

Born and raised in San Diego, California, Prior engaged Tom House as his pitching tutor in high school. A career at the University of Southern California, where he won the Golden Spikes Award, saw him become one of the top prospects in the 2001 MLB draft, when he was the second overall pick by the Cubs. He made only six appearances in the minor leagues before debuting with the team in 2002. In 2003, he finished third in National League (NL) Cy Young Award voting, ranking among the leaders with 18 wins, a 2.43 earned run average (ERA), and 245 strikeouts. Helping the Cubs win the NL Central title, he outpitched Greg Maddux in the NL Division Series and won Game 2 of the NL Championship Series, but he was on the mound for Game 6 when Steve Bartman prevented Moisés Alou from catching a foul ball (Bartman was one of several fans who attempted to catch the foul ball that was clearly in the stands).

Prior had pitched a scoreless game up to this point, but the Florida Marlins went on to win the series in seven games after an eighth inning eight-run rally in that game, in which Prior received the loss. In 2004, he was on the disabled list twice but finished the season with a 16-strikeout performance against the Cincinnati Reds. He made 27 starts with the Cubs in 2005 and finished ninth in the NL in strikeouts despite missing some time due to injury. Multiple injuries limited him to nine games in 2006, and he did not pitch at all in 2007 due to tears in his labrum, anterior capsule, and rotator cuff. After the season, the Cubs non-tendered him, letting him become a free agent.

Prior never pitched in the major leagues again after that, though he tried several times. He pitched in the minor leagues for multiple organizations over the next six years before finally retiring at the end of the 2013 season. Once touted as having perfect "pitching" mechanics by The Sporting News, his "Inverted W" arm action has been discussed as a possible reason for his lack of durability, as well as Dusty Baker's heavy usage of him during the 2003 season, though Prior himself does not blame Baker for his injuries. Prior accepted a front office position with the San Diego Padres in 2013, then joined the Dodgers, becoming their pitching coach in 2020.