Sean William Newcomb (born June 12, 1993) is an American professional baseball pitcher in the Boston Red Sox organization.

He has previously played in Major League Baseball (MLB) for the Atlanta Braves, Chicago Cubs, and Oakland Athletics.

As a freshman for the Hartford Hawks baseball team in 2012, Newcomb started nine games before suffering a season-ending injury.

[11] Newcomb was assigned to the Single–A Burlington Bees and later, in 2015, promoted to the Double–A Arkansas Travelers,[12][13] where he ended his first full season in professional baseball; he had a combined 2.38 ERA across 3 levels.

[14] On November 12, 2015, the Angels traded Newcomb, Erick Aybar, Chris Ellis, and cash considerations to the Atlanta Braves for Andrelton Simmons and José Briceño.

[29] Newcomb completed the seventh inning in his next game against the Miami Marlins,[30] but struggled against the New York Mets,[31] leading to his demotion to the Gwinnett Stripers on April 14.

[42][43] Newcomb endured an abysmal 2020 season, registering an 11.20 ERA in 13.2 innings pitched across 4 games, striking out 10.

Newcomb allowed five runs in an inning of work in an 18–4 loss against the New York Yankees and was designated for assignment after the game.

On August 4, Newcomb was selected back to the active roster to start the second game of a doubleheader against the St. Louis Cardinals.

[52] In 20 appearances split between the Single–A San Jose Giants and Triple–A Sacramento River Cats, he registered a cumulative 3.15 ERA with 45 strikeouts in 34+1⁄3 innings pitched.

[55] After posting a 3.00 ERA across 7 appearances for Oakland, Newcomb was placed on the injured list with a sprained left knee on September 17.

[56] On September 20, it was announced that Newcomb had undergone left knee lateral meniscus surgery, ending his season;[57] he was transferred to the 60-day injured list the same day.

[59] On December 20, Newcomb underwent an arthroscopic surgery on his right knee, with the procedure projected to have him ready for game action by spring training.

With the A's trailing the Minnesota Twins 5–4 in the eighth inning, Newcomb entered in relief of Lucas Erceg with a runner on first and two outs.