|Place of death||Kilrah System|
|Service/branch||Terran Confederation Navy|
|Commands||TCS Tarawa, Strike Force Valkyrie|
|Battles/wars||Raid on Kilrah|
Commodore Thaddeus O'Brian begun his naval career at the Academy. After he graduated from the Academy he dinged a destroyer in a docking maneuver and ConFleet pulled him off to transport command where he spent twenty-nine years before being sent back to an office on Earth. He had a hand in the design of the Wake-Class Escort Carrier. He aided in the conversion of the medium transports to the CVE design, something he took particular pride in.
His knowledge of transports aided him in securing the Captain's job on TCS Tarawa. He believed that getting a red combat tag in his file would aid him in his climb through ConFleet. He never thought that Tarawa would see large-scale combat. He was unaware of its upcoming role in Operation Back Lash as the heart of Strike Force Valkyrie. He was surprised when Tarawa was rerouted to Vukar Tag for the opening moves in the operation.
O'Brian faced his new command with cowardice. He possessed a strong dislike for his Wing Commander, Lt. Commander Jason Bondarevsky and this strained the command relationship. He was killed during the Kilrah Raid when a Strakha made a kamikaze attack into the bridge of the Tarawa in the middle of an argument with Bondarevsky. O'Brian had elected to retreat when a Kilrathi carrier entered the system, thereby abandoning the Marines on the surface of Kilrah's second moon. Jason Bondarevsky assumed command of the strike force and was able to rally the survivors and organize a retreat to Confederation space.
His face is lined with deep set wrinkles with dark intense eyes. He was balding. He tried to hide this through the use of a comb over, however, it did little to hid the fact. Bulbous nose, heavily veined and dark red: a drinker's nose. Overweight, shoulders slightly hunched, weak grip, clammy palms, and shifty eyes when uneasy were the common description of his physique.
He has a maddeningly inconsistent behavior: one minute, almost too friendly with his subordinates, the next, climbing up on his high horse to lecture and shout. He knows nothing about the running of flight operations, has a big grievance with pilots, refuses the advice of others and tries to make himself sound more important. He was known to drink on duty. Bondarevsky noted that others often found him smelling of his favourite Sherry during duty hours.