Oh lawd!
Of course, both are actually take inspiriation from real life, and no, not the KKK. They again take inspiration from an actual organization older than they.
At any rate, I wonder which influenced GOI? Pointy hats and halberds fir the palpal knights of hellsing to a T, but that's not to say it's what they're using as inspiration.
Speculation on pointy hats hooooo!