Jack Sloper was a Beater on the Gryffindor Quidditch team in 1995. Along with Andrew Kirke, he took over for Fred and George Weasley. He and Kirke were both described as incompetent; this was particularly evident when Sloper knocked himself unconscious with his own bat. He expressed interest in continuing to play for Gryffindor, but was replaced the following year.
Sloper later delivers a message for Albus Dumbledore to Harry Potter with the details of their first lesson.
During his sixth year he managed to join Mylor Silvanus, Jimmy Peakes and Colin Creevey to escape of the Hogwarts professors and fight in the Battle of Hogwarts. Jack picked up his broom and flew with his friends against Voldemort's army. Along with Andrew and Ritchie Coote and he managed to disarm lockout several dementors and a giant. Jack survived the battle and later married an muggle and had a son.