The Murderer role is a very important Power Role used in the Ambush games. This and the Protector role are the only two roles to be used in every game so far. Only the scum have had the Murderer role so far. If you're the Murderer, your night action is to attempt to murder one loyalist every night. This could fail though, as the Protector role allows one loyalist to be protected from murder each night. If the Murderer tries to kill a protected loyalist, the murder will fail.
The Murderers so far are:
Starkiller (Ll)- Sith Temple
General Grievous (Ll)- Haters Of The Jedi II: Order 66