Halloween Costumes - Is There a Tradition?

Cubelick on Twitter has asked about Halloween costumes, whether there are any particular traditions behind Halloween costumes. And I wondered if there are any once really popular costumes that we don't maybe see anymore. The costumes I understand are stereotypical ones of which is putting on a white sheet, looking ghoulish, trickle of blood round the mouth,. Putting on pointy hats, as you say, putting on black or basically enacting stereotypes from art and literature.