President Lincoln became famous for topping his outfits with an extra-tall stovepipe hat, and there's just no way to complete a Lincoln look without one. Simply add your favorite black suit and some stubble (real or faux) and you're all set.
While this political costume requires more of a costuming effort than most of the others on this list, the odds of leading your Halloween party in a spontaneous musical number are also proportionally higher, which seems like a worthy tradeoff.
Ruth Bader Ginsburg
This Stella & Dot necklace is the exact version that RBG wore for the first official Supreme Court portrait with Brett Kavanaugh (it was gifted to her by a fan) affording your costume extra authenticity points.