Don Hagarty is a young homosexual man in Derry, the life partner of Adrian Mellon, and a minor character in the novel, It. Before Adrian came into his life, Don was planning on leaving Derry, not just because of its violent homophobic attitude but because of the evil presence that lives in the sewers under the city.

Before Adrian leaves, the two attend a town fair and are harassed by three homophobic teens, John "Webby" Garton, Steven Bishoff Dubay and Chris Unwin on the way home. After the youths throw Adrian over a bridge and continue beating up Don, the police arrive and stop the fight. When Don and Chris witnessed Pennywise attacking Adrian under the bridge, they tried to tell the police and both John and Steven, but they didn't see anything. After Adrian's body was found and buried in the Derry Cemetery and both John and Steven were sent to prison, nobody mentions Pennywise at the trial and both Don and Chris leave Derry.