- For other uses, see O'Brien.
In the mirror universe, the ISS O’Brien (NCC-71300-B) was a Terran Odyssey-class dreadnought in Imperial Starfleet service in the early 25th century. The ship contained technology to maintain a trans-dimensional rift between the mirror and the primary universes.
In the year 2409, the O’Brien was the flagship of an Imperial fleet attacking Romulan Republic starbase Vauthil Station. A combined task force consisting of Starfleet, KDF and Republican forces defended Vauthil Station against the invasion fleet, closed rifts and activated relays to power up the station's defenses. The Allies were directed by Obisek. The O’Brien entered the battle after a sizeable portion of the invasion fleet was pushed back into the mirror universe by an anti-tachyon pulse from Vauthil Station, and led the remainder of the forces until its destruction. (STO mission: "Mirror Invasion")
- During the event, one named Galaxy- or Odyssey-class dreadnought is chosen randomly by the game software.