Josh Ronald Hader (born April 7, 1994) is an American professional baseball pitcher for the Milwaukee Brewers of Major League Baseball (MLB). The Baltimore Orioles selected him in the 2012 MLB draft . He was traded twice before joining the Brewers in 2015. Hader played for the United States national baseball team in the Pan American Games in 2015, and appeared in the All-Star Futures Game in 2016. He made his MLB debut in 2017.
Hader attended Old Mill High School in Millersville, Maryland , where he played for the school's baseball team. As a senior, Hader had a 10–0 win–loss record , a 0.30 earned run average (ERA), and 125 strikeouts . He also had a batting average above .400.  
After graduating from Old Mill High School, Hader was prepared to enroll at Anne Arundel Community College . The Baltimore Orioles selected Hader in the 19th round of the 2012 Major League Baseball (MLB) Draft , with the 582nd overall selection.  He signed with the Orioles for a $40,000 signing bonus , rather than attend Anne Arundel.   Beginning his professional career, Hader's fastball velocity increased from 84 to 88 miles per hour (135 to 142 km/h) as a high school player to 94 to 95 miles per hour (151 to 153 km/h) as he changed his workout routine. 
Hader played for the Gulf Coast Orioles in the Rookie-level Gulf Coast League and the Aberdeen Ironbirds of the Class A-Short Season New York–Penn League , allowing only 14 hits and nine walks while striking out 48 in 28 2 ⁄ 3 innings pitched .  In 2013, the Orioles assigned Hader to the Delmarva Shorebirds of the Class A South Atlantic League (SAL). He appeared in the SAL All-Star Game,  and through July 31, pitched to a 3–6 record with 79 strikeouts and a 2.65 ERA in 17 games started . 
On July 31, 2013, the day of the MLB trade deadline , the Orioles traded Hader and L. J. Hoes to the Houston Astros in exchange for Bud Norris .   He completed his 2013 season with the Quad Cities River Bandits of the Class A Midwest League .  Pitching for the Lancaster JetHawks of the Class A-Advanced California League in 2014, Hader and two relief pitchers combined to throw a no-hitter on May 13.  After pitching to a 9–2 record with a league-leading 2.70 ERA and 112 strikeouts in 103 1 ⁄ 3 innings, the Astros promoted him to the Corpus Christi Hooks of the Class AA Texas League in August. He was named the California League Pitcher of the Year.  Hader returned to Corpus Christi in the 2015 season.  He was selected to play for the United States national baseball team in the 2015 Pan American Games . 
On July 30, 2015, the Astros traded Hader, Brett Phillips , Domingo Santana , and Adrian Houser to the Milwaukee Brewers for Carlos Gómez and Mike Fiers .  The Brewers assigned Hader to the Biloxi Shuckers of the Class AA Southern League .  He finished the season with a 3.03 ERA combined. The Brewers invited him to spring training in 2016. 
Hader began the 2016 season with Biloxi, and made his first start for the Colorado Springs Sky Sox of the Class AAA Pacific Coast League on June 12.  He was selected to appear in the 2016 All-Star Futures Game .  The Brewers added him to their 40-man roster after the season.