Captain Slavin (voiced by André Sogliuzzo) is the second in command of Grand Admiral Thrawn.
Star Wars Rebels
He is first appeared in "Hera's Heroes" in season 3 as nemesis of Cham Syndulla and later of Hera Syndulla. He held both Hera and Ezra Bridger hostage to force Cham to trade himself for their lives. However, Cham, Ezra and Hera escape with help from the Ghost crew.
In the episode, "In the Name of the Rebellion: Part 2", he commands a Star Destroyer to take a large kyber crystal. He is killed with his crew when the crystal damaged by Saw Gerrera blows up, destroying his ship.