Undrafted out of High School at Andover Academy, Hathaway played four seasons at Brown University before signing with the Calgary Flames in 2015. Garnet’s hard physical style translated into professional success when he broke into the Flames lineup in the 2016-17 season. One of the league’s most consistent hitters and players, Hathaway’s hard work paid off with a well-deserved four year contract with the Washington Capitals in July of 2019.