Tiaan Jerjerrod is a human Imperial moff and rear admiral from Tinnel IV, played by Michael Pennington in Return of the Jedi (1983). He commands the second Death Star, and his single scene is a performance review.
The opening scene
Vader arrives, observes that construction is behind schedule, and declines every excuse offered. Jerjerrod's defence — that his men are working as fast as they can, that the Emperor asks the impossible, that he needs more men — is the most relatable dialogue any Imperial officer is given, and the film plays it for exactly that. He is a project manager being told the deadline has moved.
An engineer, not a warrior
The background material makes him a starship designer and architect who worked on the first Death Star and rose on technical merit rather than command experience. That is the source of the scene's tension: he is not frightened of Vader the way a soldier would be, he is frightened the way a contractor is when the client turns up on site.
Endor
During the battle the Emperor authorises him to fire the superlaser at the Rebel fleet, which he does — the only time in the saga the Death Star is used as a ship-killer rather than a planet-killer. He dies when the station is destroyed. Later canon material gives him descendants on both sides of the sequel-era war, which is a neater piece of continuity than the character strictly needed.
