How to Host a Harry Potter Movie Marathon
Invitations and Flyers
Use light brown printer paper to give your invitations and flyers a parchment type look. If you want them to look even older, use a lighter to burn the corners and edges.
Placing black or purple fabric on the tables will give them a wizard type look. Also lighting candles and lanterns instead of lamps will help set a magical mood. Also if the weather is right and you own a projector, you can show the movies outside on the side of a fence or building and natural moon and starlight will set the ambiance for you. If the party must be held indoors, another type of projector, one that projects stars onto the ceiling, can give you the feeling of being in the great hall. Black lights also make a cool effect.
Use little plastic cauldrons to make goodie bowls for each person. They sell specific Harry Potter candy but it's usually expensive and tastes just like (or in some cases a lot worse) than similar cheaper candy. Instead of Every Flavor Beans, just buy Jelly Bellies. They are less expensive and you can avoid flavors like vomit and booger (unless of course you want those). Jelly Bellies still have the weird flavors like toasted marshmallow. If everyone at the party is over twenty-one, butterscotch schnapps is what I've always pictured butter beer tasting like. If it's a party for children than bottled ginger ale is an ok substitute. Licorice wands are easy, and Twizzlers come in all varieties of colors and flavors. Chocolate frogs can be accomplished with a soft fudge recipe and a mold of a frog. Pumpkin pasties can be made by making a few pumpkin rolls and cutting them into pieces. When setting up a table for refreshments, everything looks more magical in a glass or a glass jar. If you use jars of different shapes and colors it will look like the table in a potion master's laboratory.
Odds are everyone at the party has seen the Harry Potter movies several times and the real reason for this type of gathering is to socialize. There are lots of Harry Potter themed board and card games that you can purchase and play with your guests.