Characters & Places:
* DumbledoreArmy
* TheWeasleyTwins
* HogwartsExpress
* ForbiddenForest
* HalfBloodPrince
* SnapesArmy
* TheGoldenTrio
* RavenclawPride
* SlytherinRules
* HufflepuffLove
* GryffindorBrave
Spells & Creatures:
* WingardiumLeviosa
* AlohomoraMaster
* ExpectoPatronum
* RiddikulusLover
* NifflerFan
* ThestralRider
* PhoenixTears
* MandrakeScream
* BoggartBasher
Quotes & Phrases:
* MischiefManaged
* Always
* IOpenAtTheClose
* TheBoyWhoLived
* HarryPotterFan
* PotterheadForever
* TheChosenOne
* HeWhoMustNotBeNamed
More Creative & Unique:
* DobbyIsAFreeElf
* HermioneGrangerBrain
* RonWeasleyIsMyHero
* TheMarauder'sMap
* PrioriIncantatem
* TheChamberOfSecrets
* TheOrderOfThePhoenix
* TheDeathlyHallows
Remember:
* You can combine these ideas to create something even more unique. For example: "DumbledoreArmyFan" or "ThestralRiderForever".
* If you want something truly obscure, look to the books for more niche details, like a character's middle name or a specific spell's Latin incantation.
* Consider your preferred username length and character limits on the platform you're using.