Colin Farrell and Vince Vaughn will assume the mantle of lead roles in the second season of the acclaimed crime series.
HBO top brass confirmed the hires on September 23 and said Justin Lin will direct the first two episodes when shooting on the eight-part series gets underway this autumn in California.
Farrell will play a police officer embroiled in a conspiracy in the aftermath of a murder.
It is understood his character will be torn between his loyalty to a corrupt department and the crime lord who controls him.
Vaughn will play the mobster whose empire is challenged after the murder of a business partner.
The other leads had not been confirmed at time of writing.