Juno Temple and Jesse Plemons are the latest names to be linked to Black Mass.
Black Mass will tell the story of Boston crime kingpin Whitey Bulger, who will be played by Johnny Depp.
The Hollywood Reporter has revealed that both Temple and Plemons are in talks to appear in the Scott Cooper directed film.
Temple has been linked to the role of prostitute Deborah Hussey - the stepdaughter of one of Bulger's lieutenants - while Plemons is discussing playing Kevin Weeks - one of Bulger's inner circle.
Depp is already on board the film, while Joel Edgerton will play FBI agent John Connolly and Guy Pearce has been cast as Billy Bulger.
Black Mass will be just the third feature film for Cooper, having delivered Crazy Heart and Out of the Furnace in recent years.
The movie is based on the book Black Mass: The True Story of an Unholy Alliance Between the FBI and the Irish Mob by Dick Lehr and Gerald O'Neill.