Classical Art
As previously mentioned, going as a work of art on Halloween is always a great idea. And there are so many different types of art to choose from, you can reuse this idea (and the frame) year after year. This is also an idea that can involve more than one person, take a look.

These two women went to a Halloween party as the Mona Lisa and Girl with a Pearl Earring. They stole the show, and admittedly, they look great! Additionally, unlike the other individual on this list that dressed as artwork, these ladies used foam to create the frame of their outfit so it would be more comfortable and easier to maneuver.