As always, if you would prefer to live in a world where spoilers do not exist and Downton Abbey does not air three months beforehand in the U.K., thus ruining all possible surprises, then stop reading! But yes, Paul Giamatti will appear on the season-four finale as Cora’s “playboy brother†Harold Levinson (you know, the one who has the other half of the fortune that could save Downton Abbey). Shirley MacLaine will return as Mrs. Levinson, presumably to help Giamatti gloat over the Granthams’ continued financial troubles; Diddy still has not been cast.