A Flag Captain represented a high-ranking officer rank within the Galactic Empire. This title was bestowed upon the person who captained the flagship belonging to an admiral. We see that Albus Marinith held the position of Flag Captain on the Chimaera, which served as the flagship for Grand Admiral Thrawn and his Seventh Fleet. Similarly, Firmus Piett was the Flag Captain of the Executor, the flagship under the command of Dark Lord of the Sith Darth Vader and Admiral Kendal Ozzel.