Marc Walter Rzepczynski (/zəpˈtʃɪnski/ zəp-CHIN-skee; born August 29, 1985), nicknamed "Scrabble", is an American former professional baseball pitcher.

He played in Major League Baseball (MLB) for the Toronto Blue Jays, St. Louis Cardinals, Cleveland Indians, San Diego Padres, Oakland Athletics, Washington Nationals, and Seattle Mariners.

In 2008, Rzepczynski advanced to the Class A Lansing Lugnuts of the Midwest League, where he finished 7–6 with a 2.83 ERA in 22 starts, with 124 strikeouts and 42 walks over 121 innings pitched.

His 2009 statistics between Double-A and Triple-A combined for 16 games (all starts), with a 9–5 record, a 2.66 ERA, 104 strikeouts, and 40 walks, in 88 innings pitched.

Richmond, before play on July 6, ranked 16th of 40 eligible American League pitchers in Earned Run Average (ERA).

In his second big-league start, Rzepczynski again pitched well, but took the loss against the Baltimore Orioles on July 12, lasting 6 innings and allowing 3 earned runs; Toronto lost the game, 4–2.

Jays manager Cito Gaston stated before the game that Rzepczynski would remain in the rotation for at least the next couple of weeks, pending Richmond's return from the disabled list.

He was traded on July 27, 2011, to the St. Louis Cardinals along with Octavio Dotel, Edwin Jackson and Corey Patterson for Colby Rasmus, P. J. Walters, Trever Miller and Brian Tallet.

[10] On December 2, 2015, the Padres traded Rzepczynski and Yonder Alonso to the Oakland Athletics for Drew Pomeranz, José Torres, and a player to be named later or cash considerations.

[19] On February 8, 2019, Rzepczynski signed a minor league deal with the Arizona Diamondbacks that included an invitation to spring training.

[23] In May 2021, Rzepczynski was named to the roster of the United States national baseball team for the Americas Qualifying Event.