Gregory Wyatt Mills (born January 25, 1995) is an American professional baseball relief pitcher in the Boston Red Sox organization.

[5] Mills signed with Seattle and made his professional debut with the Everett AquaSox before earning a promotion to the Clinton LumberKings.

[6] In 2018, he began the year with the Modesto Nuts, with whom he went 6–0 with 11 saves and a 1.91 ERA in 42+1⁄3 innings pitched and was named a California League All-Star.

[10] On June 27, 2022, Mills and minor-league starting pitcher William Fleming were traded to the Kansas City Royals in exchange for Carlos Santana.

[15] Through the end of the regular season, Mills pitched in 19 games for Kansas City, striking out 20 batters in 20+2⁄3 innings with a 4.79 ERA.

[18] He suffered additional elbow inflammation in mid-March, delaying his recovery,[19] and was transferred to the 60-day injured list on April 16.

[23] In October 2019, Mills was selected for the United States national baseball team for the 2019 WBSC Premier12 tournament, held in November 2019.