Zoe Boyle, Cal Macaninch, Iain Glen, Amy Nuttall and Maria Doyle-Kennedy have all signed up for roles in the period drama, which will return to ITV later this year.
Boyle, known for her role as Trinity Ashby on FX drama Sons of Anarchy, will play Miss Lavinia Swire, while former Holby Blue star Macaninch will appear as Lang, a new valet.
Ex-Emmerdale actress Nuttall will play new housemaid Ethal. Glen, due to appear in new HBO series Game of Thrones, will portray Sir Richard Carlisle, and Doyle Kennedy will appear as Vera, the wife of John Bates (Brendan Coyle), having previously appeared in The Tudors and Dexter.
Downton Abbey concluded in November last year, reaching an aggregate audience of 12.8 million viewers.The second eight-part series of will be followed by a one-off special at Christmas.