|Miles Edward O'Brien|
|Position||Chief of operations|
|Age||Born September 2328|
Miles Edward O'Brien was a 24th century Human man, born on September 1, 2331. He has served Starfleet as tactical officer aboard the USS Rutledge during the Federation-Cardassian War, transporter chief aboard the USS Enterprise-D from 2364 to 2369, chief of operations aboard starbase Deep Space 9 from 2369-2375, chief engineer of the USS Defiant from 2371 to 2375, and as an instructor at Starfleet Academy beginning in 2376. In 2383, O'Brien was assigned to oversee construction of the second Deep Space 9 space station.
O'Brien was introduced to Keiko Ishikawa by their mutual friend, Data. The two eventually wed aboard the Enterprise-D in a wedding ceremony that combined Irish and Japanese traditions. Data served as the "father of the bride." Together, Miles and Keiko O'Brien had their first child, Molly, who was born in early 2368. Keiko gave birth to the child in the Enterprise's Ten Forward lounge during a ship-wide systems failure. Kirayoshi O'Brien was born in 2373 while living on Deep Space 9, the second child of Miles and Keiko O'Brien. Kira Nerys acted as a surrogate mother for Kirayoshi after Keiko was injured during a mission to the Gamma Quadrant in late 2372, carrying the baby to term. Kirayoshi's name was often shortened to "Yoshi."
Miles "Smiley" O'Brien was a Terran slave who worked for the Klingon-Cardassian Alliance aboard station Terok Nor, but later became the leader of the Terran Resistance Forces who fought the Terran Rebellion.
In 2370, O'Brien was working in the station's ore processing center, and had the slave classification "theta", which was a relatively respected and privileged position. O'Brien was also occasionally recruited to repair Benjamin Sisko's raider when it was docked at the station. Sisko claimed he hated the name Miles, and instead nicknamed O'Brien "Smiley", despite of Smiley's lack of approval. He had a good reputation on the station for being an excellent "tinkerer and putterer".
When Smiley met a Julian Bashir from another universe in the ore processing center, he initially thought that Bashir's "wild" tales of his counterpart being Chief of Operations was simply a ruse to get him to help Bashir. However, Bashir's earnest attitude won him over, along with the realization that anything had to be better than his slavery to the Alliance. Smiley helped Bashir try to escape from the station, on the condition that he be taken along to the other side.
However, when Captain Sisko also rejected Intendant Kira Nerys's authority, Smiley changed his mind and decided to join Sisko's crew, deciding that there was something worth staying for after all.
When Captain Sisko was killed by the Alliance in early 2371, Smiley took charge of the Terran Rebellion. In order to complete Sisko's last mission, he recruited Benjamin Sisko from the other universe to take the place of his deceased counterpart long enough to convince Jennifer Sisko to leave the Alliance and start working for the Rebellion.
While he was aboard Deep Space 9, Smiley took the opportunity to download a large portion of the station's database, including the schematics for the USS Defiant. This information came in handy the next year, when the rebels managed to capture Terok Nor from the Alliance. Smiley used the stolen specifications to build the rebels' own warship, which they also christened Defiant. However, with the Alliance about to launch a counterattack to recapture the station, Smiley once again recruited Sisko in order to help them finish construction of the Defiant in time.
Smiley piloted the ISS Defiant during the Battle of Terok Nor, although he was replaced by Sisko partway through, because Sisko had greater experience flying the little warship. Following the successful conclusion of the battle, Smiley sent Sisko back home.
In 2375, Smiley was still in command of the rebellion on Terok Nor. He commanded the Defiant when it pursued Brunt's ship as it stole a cloaking device from the station, and later negotiated Regent Worf's surrender and capture.