Special bridge officer

A Special Bridge Officer is a bridge officer which is unique in some way. They are typically acquired in an atypical way, such as a mission reward, C-Store purchase, or completion of a Reputation. Many special bridge officers officers cannot be customized at the Tailor.

Tutorial bridge officers

These bridge officers are acquired through completion of each faction's tutorial and early storyline missions. All of the Uncommon tutorial bridge officers are unique in that they have four Standard-tier traits, which is an impossible loadout on standard bridge officers you can obtain throughout the game. Some of the others have other unique qualities to them, noted below.

Federation (23rd century)

[Tarsi] (23c Andorian); awarded upon completion of “Dislodging Klingons”. Unique trait loadout: no Cold Dwelling.
[Skavrin] (Tellarite); awarded upon completion of “In the Shadow of Cestus”. Unique trait loadout: no Sturdy.
[T'Met] (Vulcan); awarded upon completion of “Painful Omens”.

Federation (25th century)

[Elisa Flores] (Human); awarded upon completion of “Training Cruise”. Unique traits: Superior Soldier, Superior Teamwork; 3 Superiors total.
[Zarva] (Bolian); awarded upon completion of “Field Promotions”
[T'Vrell] (Vulcan); awarded upon completion of “Communications Breakdown”
[Kolez] (Saurian); awarded upon completion of “Assimilation of the Innocent”

Klingon Empire

[K'Gan] (Klingon); awarded upon completion of “Challenge for Command”. Unique trait: Superior Honorable; 3 Superiors total.
[Ch'gren] (Klingon); awarded upon completion of “Duties of Command”
[Thraak] (Gorn); awarded upon completion of “Space Chase”. Unique trait: Creative.
[B'Ellera] (Klingon); awarded upon completion of “Bringing Down the House”

Romulan Republic

[Tovan Khev] (Romulan); awarded upon completion of “Virinat, Invaded”. Unique traits: Superior Soldier.
[Veril] (Reman); awarded upon completion of “Crossroads at Crateris”.
[Satra] (Romulan); awarded upon completion of “The Helix”.
[Hiven] (Romulan); awarded upon completion of “Gasko Blues”.
[D'Vex] (Romulan); awarded upon completion of “Devil's Choice”. Unique traits: Space Warfare Specialist, Veteran; 1 Superior and 3 Standard.

In-game rewards

These bridge officers are acquired as mission rewards, or other in-game means.

Mission

Breen Tactical Officer Candidate - A reward for completing the Breen featured series arc before October 14 2010 or during the occasional Featured Series Rerun.
Hierarchy Science/Intelligence Officer Candidate - Awarded upon completion of “Alliances” mission in the Delta Quadrant arc.
Jem'Hadar Tactical Officer Candidate - Rewarded to players who completed “Facility 4028” mission from the Cardassian Struggle arc.
Kobali Engineering/Command Officer Candidate - Female Kobali, awarded upon talking to the lost Kobali in the maze during the “Dust to Dust” mission, added during the Fifth anniversary event.
Reman Science Officer Candidate - Male Reman, rewarded to players who completed “Cutting the Cord”, the final mission of the Romulan featured series, before March 24th 2011 or during the occasional Featured Series Rerun.

Reputation

Borg Science Bridge Officer Candidate - Male liberated Borg Science officer, attainable by completing a Tier 5 Task Force Omega reputation project or by completing the Assimilated accolade in “Khitomer in Stasis”.
Voth Science Officer Candidate - Male Voth, rewarded to players for completing “Unsaid Thanks”, after the player completes Tier 5 of the Dyson Joint Command Reputation System.

Recruitment Event

Photonic Engineering Officer Candidate - Male-programmed Photonic, account wide unlock upon completing all story missions as a single Delta Recruit.

Commendation

Federation Enemy Faction Bridge Officer - an officer from certain KDF races (Orion, Nausicaan, Gorn) awarded by Jiro Sugihara to Federation-aligned players for reaching the diplomatic rank of Ambassador.
KDF Enemy Faction Bridge Officer - an officer from certain Starfleet races (Andorian, Ferengi, Human, Trill) awarded by Marauder Kazzgur to Klingon-aligned players for reaching the commendation rank of Marauder.

Purchaseable

C-Store

These bridge officers are exclusively acquired through the C-Store with Zen.

Aenar Bridge Officer - Available for 500 per officer through the C-Store. Only available to Starfleet captains.
Caitian Bridge Officer - Available for 500 per officer through the C-Store. Only available to Starfleet captains. Also available as a common Intelligence officer for 200 dilithium in game from the bridge officer store.
Ferasan Bridge Officer - Available for 500 per officer through the C-Store. Only available to KDF captains.
Federation Liberated Borg Bridge Officer - A female liberated Borg Engineering officer. Available bundled as a pre-order account-wide unlock or from the C-Store for 500. You may only have a single Borg Bridge officer active per captain. Only available to Starfleet captains.
Klingon Liberated Borg Bridge Officer - A female liberated Borg Engineering officer. Available bundled as a pre-order account-wide unlock or from the C-Store for 500. You may only have a single Borg Bridge officer active per captain. Only available to KDF captains.
Reman Liberated Borg Bridge Officer - A male liberated Borg Tactical officer. Available bundled with the Legacy Pack or individually from the C-Store for 500. Only available to Romulan Republic captains.
Delta Rising Bridge Officers - A Tactical, Engineering, and Science Intelligence Specialist for each faction. Only available in the Delta Rising: Operations Pack for 15,000.
Starfleet 0718 Model Android Officer - An android science officer. Available bundled with the Temporal Agent Starter Pack for 2,000 and the Temporal Special Agent Pack for 13,000.

Fleet

These bridge officers are available through the Fleet holdings, costing Fleet Credits and Dilithium.

Colony World Bridge Officers - Lukari and Kentari bridge officers with unique traits available from the Fleet Colony World.
23rd Century Bridge Officers - Custom bridge officers with K-13 Survivor traits available from the Fleet Station K-13.
Krenim Bridge Officers - Custom bridge officers with Krenim-specific traits available from the Fleet Research Lab.
Romulan Bridge Officer - Custom bridge officers with new Romulan-specific traits available from the Fleet Embassy.

Lobi Store

These bridge officers are acquired through the Lobi Store using Lobi Crystals.

Romulan Liberated Borg Science Officer Candidate - Female Liberated Borg Romulan, purchasable from the Lobi Crystal Consortium at Drozana Station for 300 Lobi Crystals.
Photonic Tactical Officer Candidate - Male-programmed Photonic, purchasable from the Lobi Crystal Consortium at Drozana Station for 300 Lobi Crystals.
Xindi-Reptilian Tactical Officer Candidate - Male Xindi-Reptilian, purchasable from the Lobi Crystal Consortium at Drozana Station for 300 Lobi Crystals.
Talaxian Intelligence Officer Candidate - Male Talaxian (Engineering, Science or Tactical profession), commissioned from the Lobi store for 300 Lobi Crystals.

Veteran reward

Rewarded for subscribing to the game for a length of time.

Starfleet and Klingon Empire Android Bridge Officer - 700 Day Veteran award.

Other

Bridge officers acquired by assorted other means.

Event giveaways

Only available during random events and giveaways.

Starfleet and Klingon Empire Emergency Medical Hologram - Promotional giveaway at Star Trek Las Vegas 2015 and a reward for participating in ExtraLife charity campaign (November 5th, 2016 to November 30th, 2016).
Holo Admiral Leeta Tactical Officer - Available to everyone who donated to the Pop Culture Hero Coalition through Groupees.com after they raised $25,000 or via the Arc Black Friday rewards promotion.
Dabo Leeta Tactical Officer - Available as a promotional giveaway at FedCon 2016 or via the Arc Black Friday rewards promotion.
TOS Holographic Bridge Officers - Promotional giveaway for visiting Star Trek conventions in 2016.
Geordi La Forge (Hologram) - Promotional giveaway at Star Trek Las Vegas 2017.

Unobtainable

These bridge officers can no longer be obtained, though existing ones are unaffected.

Starfleet and Klingon Empire Veteran Bridge Officer - These bridge officers were given to characters whose in-game wealth was significantly devalued in the conversion to the dilithium economy introduced with Season 5. They are extremely rare and have the traits Space Warfare Specialist and Veteran, which are otherwise only found on D'Vex.
Starfleet and Klingon Empire Photonic Science Bridge Officer - Rewarded via the currently-defunct Referral Program for recruiting a full subscription for one month.

Original Federation tutorial bridge officers

The original Federation Tour of Duty tutorial mission “Khitomer Crisis” offered players a choice of one of the following (no longer available) bridge officers, which are unique in that they have four standard traits, an impossible loadout on modern bridge officers. They were commissioned at common quality, become uncommon quality in the status screen, yet they have the same amount of "trait points" as a modern rare bridge officer.

Tactical Duty Officer, a female Andorian with Acute Senses, Cold Dwelling, Fury and Stubborn.
Engineering Duty Officer, a male Bolian with Corrosive Blood, Creative, Lucky and Resilient.
Science Duty Officer, a male Vulcan with Logical, Nerve Pinch, Peak Health and Physical Strength.

Steam Promo Pack bridge officers

The Steam Starter Pack came with two bridge officers that have unique trait loadouts:

The male Trill Engineering Officer Candidate has Basic Luck, Hyper Metabolism, Stubborn and Teamwork; Basic Luck and Teamwork are normally unavailable on Trill officers.
The female Vulcan Science Officer Candidate has Basic Creativity, Logical, Nerve Pinch and Peak Health; Vulcan bridge officers are normally required to have Physical Strength.

This bundle was removed from Steam and can no longer be purchased, though keys purchased prior to its removal will still work. Future characters on your account can continue to claim the officers, albeit only once, and they cannot be reclaimed if dismissed or discarded. The Steam Runner Bundle that replaced it in the C-Store does not come with the bridge officers, meaning they are now otherwise unobtainable.