Gregory Wyatt Mills (born January 25, 1995) is an American professional baseball pitcher in the Seattle Mariners organization. He was drafted by the Mariners in the third round of the 2017 MLB draft.
Mills attended Gonzaga Preparatory School in Spokane, Washington. Undrafted out of high school in the 2013 MLB draft, he enrolled at Gonzaga University where he played college baseball for the Bulldogs.
In 2014, as a freshman at Gonzaga, Mills pitched 12 ⁄3 innings, compiling a 3.65 ERA, and in 2015, as a sophomore, he went 1-0 with a 2.79 ERA in 19 innings. Mills broke out as a junior in 2016, going 3-2 with a 2.65 ERA and seven saves in 37 innings pitched in relief. He was drafted by the Tampa Bay Rays in the 17th round of the 2016 MLB draft, but did not sign. That summer, he played in the Alaska Baseball League. During his senior year, he went 2-2 with a 1.79 ERA and 12 saves in 22 relief appearances. After his senior year, he was drafted by the Seattle Mariners in the third round of the 2017 MLB draft.
Mills signed with Seattle and made his professional debut with the Everett AquaSox before earning a promotion to the Clinton LumberKings. In 20 ⁄3 innings pitched between the two club, he went 0-2 with six saves and a 1.77 ERA, striking out 29.
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 ⁄3 innings pitched and was named a California League All-Star. At the end of the season, he was promoted to the Arkansas Travelers, pitching to a 10.13 ERA in 10 ⁄3 innings. After the season, he was assigned to play for the Peoria Javelinas of the Arizona Fall League where he was 1-0 with a 1.93 ERA in eight appearances. He returned to Arkansas for the 2019 season, going 4-2 with eight saves and a 4.27 ERA over 52 ⁄3 relief innings, striking out 66.
He pitched for the United States national baseball team in the 2019 WBSC Premier 12 tournament in November 2019.