Talk about being a pantomime villain. It’s unpopular enough playing the antagonist who murders a long-running TV character. When your victim is a fan favourite, though, you risk being vilified even more. So what’s it like being the ultimate baddy and breaking viewers’ hearts? Do they get booed in the street or trolled online? We asked five actors who killed off beloved characters – from Spooks to The Sopranos, Wolf Hall to Westeros – about their experiences …