Producers have announced that Wuthering Heights actress Charlotte Riley will join the cast of the 1920s gangland drama, alongside Game Of Thrones actor Noah Taylor.
Riley, who worked with Tom Cruise and Emily Blunt on Edge Of Tomorrow, will play an aristocrat who crosses paths with Cillian Murphy's character, Tommy Shelby.
She and Hardy have worked together before, on the ITV dramatisation of the Bronte classic.
Taylor will join as the head of a rival crime organisation when the second series airs later this autumn.
The British-Australian actor played the pianist David Helfgott in his younger years in the 1996 film Shine, and has appeared in Vanilla Sky and Charlie And The Chocolate Factory.