Siobhan Finneran, who plays O'Brien on the show, will not be returning for Season 4, according to Huffington Post UK.
"I'm not doing any more," Siobhan confirms. "O'Brien is a thoroughly despicable human being — that was great to play."
So will O'Brien be meeting an untimely death, like recently departed Lady Sybil and Matthew Crawley? Perhaps not.
"When an actor playing a servant wants to leave, there isn't really a problem — [that character gets] another job," creator Julian Fellowes has said. Who knew that corporate headhunting was a thing back then?
That's a relief, as we're not sure we could handle yet another Downton death!
Sources: Huffington Post UK, ET Online