This one took about 5 hours, start to finish. I haven't entirely decided on what to be yet; either Lord Voldemort, Lucius Malfoy or a dementor. Simplicity Pattern 9887.
I added the "P" (for Prefect) emblem before sewing on the house patch and I'm looking at adding an honor guard-style agulet (shoulder rope and tassel) for a little extra color.
I just finished with my oldest daughter's Halloween costume; she decided this year she wanted to go as a Ravenclaw Prefect from Harry Potter. This one is from Simplicity pattern 3993. I added the buttons and gold border and gave it a blue lining (though next time I'll build the lining and outer layer seperately and then assemble it as a whole).
I want to go as Mr. Weasley, but she thinks I should be Lucius Malfoy. We'll see...