Hmmm… I’d prefer to be TSN, but if you’re looking for ideas:
Black graduation gowns, Hogwarts accessories: Hogwarts bridge. Gryffindor is Command, obviously, Ravenclaw is Science, equally obviously, Hufflepuff is Engineering, and Slytherin is Weapons. Comms is probably Ravenclaw as well, with another Gryffindor as Helm.
Wizard of Oz bridge: Dorothy is Command, Scarecrow is Science, Lion is Weapons, Tin Man is Engineering, Wicked Witch is Helm and Toto is Comms.
Alice in Wonderland bridge: Alice is Command, Queen of Hearts is Weapons, White Rabbit is Helm, Caterpillar is Science, Mad Hatter is Comms, March Hare is Science.
Firefly bridge: Mal is Command (duh!), Wash is Helm (double duh!), Zoe is Weapons, Kaylee is Engineering, Simon is Science, Book is Comms. River is in a box.
Some or all of the above may involve dressing as the opposite gender; deal with it.