Mitch Thomas Keller (born April 4, 1996) is a pitcher for the Pittsburgh Pirates in Major League Baseball (MLB). The Pittsburgh Pirates chose Keller in the second round of the 2014 Major League Baseball draft out of Xavier High School in Cedar Rapids, Iowa.
He signed with the Pirates on June 14, 2014, for a signing bonus of $1,000,000. He had committed to play collegiate baseball for the North Carolina Tar Heels.
Keller started the 2017 season with Bradenton. In August, he was promoted to the Altoona Curve, where he concluded the season with a 2–2 record and 3.12 ERA in six appearances after going 6–3 with a 3.14 ERA in 15 starts. Keller was regarded as Pittsburgh’s #1 prospect by MLB.com heading into the 2018 season.
Keller started the year in Indianapolis. On May 26, he was promoted to the major leagues and made his major league debut against the Cincinnati Reds at Great American Ball Park, giving up six earned runs in four innings while walking two and striking out seven.
Keller pitched for the Pirates in 2020, posting a 2.91 ERA and 16 strikeouts in 213 innings.  In 100+23 innings in 2021, he finished 5–11 with a 6.17 ERA and 92 strikeouts.
Professional pitcher for the Pittsburgh Pirates, Keller is currently married to his wife, Clancy, but the lovely couple does not have any children at the moment.