Downton Abbey Quiz

Every performer billed in the opening titles of the ITV period drama about an aristocratic family and the servants who run their Yorkshire country house, across its six series from 2010 to 2015. That is the whole rule: a billed principal is in, and the very large recurring and guest company is out, however many episodes they appeared in and however well you remember them. Three performers the article describes at length were never billed in the titles, so they are not answers here. The answer is always the actor, never the character. A surname on its own counts. Cast order follows the series billing, corroborated against Wikidata. Nothing in this set gives away the story: no question, clue, option or answer reveals how anyone's story ends.