Here is the selection for military character roles:
Notes from Dr. Bon
Military costumes are super easy - if you are a General - wear the General costume. Or, you can just get a General's hat and wear something solid color to accent just the hat.
Sailors, and boat captains (who many used to be military - so it's all good), can just wear a sailor or captain's hat or go all out with the full sailor/captain costume.
Paratroopers - you don't have to drag a parachute to the party, but at least wear a flight suit or camouflage - that's good enough! Navy Seals can just get the kit with the vest that says 'Navy Seals' and wear all black underneath.
It's always great for combat characters to smudge a bit of camo makeup on your face for a fun effect.
Or, you can always opt for an easy T-shirt to reflect which branch of the military your character is in.