“Harry Potter’’ fans understand that at least some good things must come to an end. And that’s why it probably wasn’t a shock that Sunday’s Yule Ball at the Middle East in Cambridge marked the last performance of Draco and the Malfoys, a Potter-themed rock band that plays tunes written from the perspective of Harry’s Slytherin nemesis, who’s played by Tom Felton in the Potter films. (Our favorite Draco songs include “My Dad Is Rich,’’ “Voldemort Is Awesome,’’ and “Tom Felton’s Kinda Hot.’’) The Malfoys were a part of a lineup of Hogwarts-inspired bands that included Boston favorite Harry and the Potters - also known as brothers Joe and Paul DeGeorge - who, for the record, aren’t disbanding despite the fact that the Potter series is over. “No worries; there will be a Yule Ball next year,’’ Paul tells us. The DeGeorges formed their band in 2002 when they were just 23 and 14; this was their seventh Yule Ball at the Middle East. Fans who came to Sunday’s sold-out show included 19-year-old Gryffindor Karina Gruesz, of Brookline.