Type: Intrepid Class
Mission Profile: Pathfinder and Reconnaissance Operations
Captain: T'arrah, Vulcan female (played by Mozhan MarnĂ²)
The Bellerophon is an expert exploration ship. A sturdy, quick vessel with excellent analytical abilities, the Bellerophon exemplifies Starfleet's dedication to exploring the unknown.
Type: Cochrane Class (an Intrepid variant)
Mission Profile: Technical Testbed
Captain: Emenike Nnadi, Human male (played by Nonso Anozie)
A long-range exploration vessel, outfitted with an experimental quantum slipstream drive.
Type: Sovereign Class
Mission Profile: Tactical Operations
Captain: Alvara Alba, Human male (played by Javier Bardem)
What was supposed to have been a flagship exploration vessel was turned into a veritable warship by Starfleet's Rapid Response Section. Ever since the destruction of the USS Venture, the Excalibur sees to the security of the Shackleton task force.
Type: Insignia Class
Mission Profile: Strategic and Diplomatic Operations
Captain: Brallon Jott, Bolian male (played by Tom Noonan)
Essentially a mobile embassy, staffed by the Federation's diplomatic corps. Where exploration vessels go first, the Geneva goes second.
Type: Akira Class
Mission Profile: Crisis and Emergency Response
Captain: Sonya Dougherty, Human female (played by Katie McGrath)
The Thunderchild is a heavily armed first responder, ready to assist anywhere for anything. And if need be, it can drive off hostiles before rendering medical aid to the wounded.
Type: K'vort bird-of-prey
Captain: Akula of House QoLarz, Klingon female (played by Cassidy Freeman)
The Mupwl' was the first Klingon vessel to assist with exploring the Expanse, although she's been mostly engaged in pirate-suppression missions.
Type: K'vort bird-of-prey
Captain: Yss'n, Gorn male (full CGI lizardman)
The Jajlo' was assigned to the Expanse after the destruction of the USS Venture. It's a warrior's vessel, filled to the brim with Klingon and Gorn eager to test themselves against a new enemy. The Jajlo' has been outfitted with state of the art subspace tunneling transporters which can transport large groups at once even through enemy shields, with an acceptable rate of success.
Type: Vor'cha attack cruiser
Captain: Borei of House Martok, Klingon male (played by Nathan Jones)
The Kri'stak is a command battlecruiser on an undisclosed mission, but most likely it's here to intervene if the Romulans ever try to backstab us.
Type: Valdore Class Warbird
Captain: Najak, Romulan male (played by Mark Strong)
A military escort vessel converted for deep-space exploration.
Type: D'deridex Class Warbird
Captain: T'geris, Romulan male (played by Stephen Lang)
The Aquirax is part of the newer 'C Generation' types of D'deridex, with the same overall frame as the previous generations but with up to date systems under the hood. As such it's a pure battleship with little to offer in terms of peaceful exploration. Commander T'geris is a career military man who served with distinction in the Dominion War.
Type: Faeht Class Intel-Warbird
Captain: M'Nerva, Romulan female (played by Courtney Ford)
The Korax is a light, nimble ship with a superior cloaking device. She excels at scouting missions but she packs enough of a punch to make her a good at ambushes and hit-and-run combat as well.
Type: Aves Class (?) Research Warbird
Captain: Strixin, Romulan male (played by Christopher Heyerdahl)
Strixin is a scientist, supposedly one of the most brilliant minds of the Empire. He's part of the fleet in name only. The Namtaru is his own personal project, a prototype starship reverse engineered from some alien tech. He's most likely in the Expanse to search for new technology to plunder.
Type: Valdore Class Warbird
Captain: Emony Tau, Trill female (played by Sonja Bennett)
While many Trill do serve in Starfleet, the Trill have never officially joined the Federation. Emony Tau joined the Romulan Star Empire instead, where her charisma and ruthless intelligence soon enough turned her into a propaganda piece meant to showcase the openness and fairness of Romulan society.
Type: Baratan Class Command Warbird
Captain: Vil'aura, Romulan female (played by Ruth Negga)
A command vessel designed to excel at gathering data and provide continuous tactical updates throughout a battle. The Tar'aklis never flies alone.