Harry and the Potters play in Tampa, Fla., July 12. The band is returning to Cambridge for a show Friday. (Photo: Nicole Kibert)

Harry and the Potters, known as the original wrock band — that’s wizard rock, for folks who aren’t engrossed in the Harry Potter series of books — returns to Harvard Square on Friday with the inevitable companion band: Draco and the Malfoys.

The return of Harry and the Potters, four years after “The Best Harry Potter Party EVER!” thrown by the Harvard Square Business Association to commemorate the final book in the staggeringly popular fantasy series, is being labeled “Smackdown in Hogwarts Square” as part of  “The Best Harry Potter Party EVER, Part 2!” The association’s Denise Jillson announced the event Tuesday.

The band’s founders seem as surprised as anyone that they’re coming back.

“We never quite expected this project to last as long as it has. Since our first show in our parent’s backyard, we have played over 500 shows in 49 different U.S. states and in a handful of foreign countries,” brothers Paul and Joe DeGeorge said in a statement. “We have played in libraries, bookstores, rock clubs, theaters, galleries, museums, doughnut shops, bowling alleys, pizza places, and even a pirate-supply store.”

And of course the songs are all about the world of Harry Potter, including the DeGeorges three albums and the four (and two EPs) by Draco and the Malfoys.

The legend goes that band was formed at a 2002 family party in Norwood when the expected band didn’t show up. The musical brothers — a Cambridge biotech engineer and a Tufts graduate — wrote seven songs in an hour for their own impromptu band and performed them for six people. Draco and the Malfoys, a Woonsocket, R.I., band, was formed two years later (by half-brothers) as a direct response to the DeGeorges. A Wizrocklopedia listing of bands shows nearly 900 wrock performers.

The numbers might diminish as the series winds down. The final book came out shortly before the July 20, 2007, party in Harvard Square, and Friday’s party is to mark the release of the final movie in the series, which is based on the second half of the final book.

But quidditch, a live sport based on one played in the books and movies, shows no sign of dying down in either colleges or nonschool leagues. Emerson College and the COOP are hosting quidditch clinics and an all-comers introductory game at 6 p.m. Friday on Palmer Street in Harvard Square. Managers at the store said the expected the game to go until about 8 p.m.

Meanwhile, MC Kreacher plays a musical set at 7 p.m.; Draco and the Malfoys perform at 7:45 p.m.; and Harry and the Potters take the stage at 8:45 p.m.

There are also shops, offices and eateries highlighting Harry Potter wares, including Cardullo’s gourmet shop selling chocolate frogs and Bertie Botts Beans; the bakery Sweet, selling cupcakes with Harry Potter character decorations; and restaurant and bar Grendel’s Den, which will have a special drink menu for kids ($2.50 or $3 drinks such as The Elixir of Life, or chocolate milk with a “Sorcerer’s Stone” at the bottom, and the Felix Felicis, or ginger ale flavored with vanilla) and adults ($6.50 for The Ginny Weasley, made with gin, orange juice and Pimm’s, or The Ron Weasley, made with Bacardi Dragon Berry, strawberry puree, lemon and mint). The cosmetics shop Lush is throwing its own party within a party from 5 to 10 p.m., with make-your-own potions, drinks and games.

The Harvard Museum of Natural History has Harry Potter programs featured during its extended hours (5 to 8 p.m.) and half-price admission days, the fourth Wednesdays of August and September. (August’s date is this week.) Details and a poster can be downloaded here.

This post took extensive information from a press release.