"Spock's Brain" was the 61st episode of Star Trek: The Original Series, and the sixth episode produced in the third and final season of TOS. Shown out of order, this episode was aired as the season premiere of the third season on 20 September 1968. Directed by Marc Daniels, this episode was written by Lee Cronin. A remastered version was released on 9 June 2007.



Episode charactersEdit

Clifford Brent (?) • Christine ChapelPavel ChekovBill HadleyKaraJames T. KirkRoger LemliRyan LeslieLumaLeonard McCoyMontgomery ScottSpockHikaru SuluNyota Uhuraunnamed USS Enterprise (NCC-1701) personnel

Novelization charactersEdit

Christine ChapelPavel ChekovKaraJames T. KirkLumaLeonard McCoyMontgomery ScottSpockHikaru SuluNyota Uhura

Starships and vehiclesEdit

Eymorg starshipUSS Enterprise (Constitution-class heavy cruiser)


Shipboard locationsEdit


Stars and systemsEdit

Sigma Draconis

Planets and planetoidsEdit

Sigma Draconis IIISigma Draconis IVSigma Draconis VI
Referenced only 

Races and culturesEdit

HumanSigma Draconis VI native (MorgEymorg) • Vulcan

States and organizationsEdit





autonomic nervous systembloodboilbrain (ganglionmedulla oblongataspeech center) • nervestomachvocal cord

Technology and weaponsEdit

biobedcommunicatorcomputercontrol braceletControllerelevatorUSS Enterprise (NCC-1701) library computerforgeGreat Teacherhand-held weaponheating plantion driveion propulsionmagnetic lockneedleneural stimulatornuclear pilepain bandphaserphaser pistolpistolremote controlsensorsledgehammersonic separatorspaceshipstarshiptapetraining devicetransferal beamtri-laser connectortransportertricorderturbolifttype-2 phaserviewscreenwater purifier

Substances and energiesEdit

iceionion powerion trailnitrogenoxygenwater

Ranks and titlesEdit

captainchief engineerchief medical officercommandercommanding officercommunications officerdoctorensignFederation Starfleet ranksFederation Starfleet ranks (2260s)first officerhelmsmanlieutenantlieutenant commandermanagermistressnavigatorpriestessscience officersecuritytactical officer

Other referencesEdit

alienanatomyatrophybreadcaptain's logcaptain's log, USS Enterprise (NCC-1701), 2268cityclass M planetclothingcommunicationsdeaction shiftenergyevolutiongalaxyglacial agegovernmenthourindustrial developmentindustrial scalelanding partylife supportlifeformlog entrymilematternation-stateorbitphysiologyplanetplanetary classificationraces and culturesrankRichter scale of culturesapient lifeship's logship's log, USS Enterprise (NCC-1701)spacesplinterstandard interstellar symbolsstarstar systemStarfleet uniformStarfleet uniform (2265-2270)starship designstellar classificationsurgerytechnologytemperaturetimetitleuniformuniversevolcanoVulcan physiologyweapon


Earth's technological and civilizational development in 1485 had an industrial scale rating of "B" and closely matched the development of the inhabitants of Sigma Draconis III in 2268. (episode)
Earth's technological and civilizational development in 2030 had an industrial scale rating of "G" and closely matched the development of the inhabitants of Sigma Draconis IV in 2268. (episode)
Enterprise encounters the Eymorg starship. (episode)
24th century 
By the 24th century, many Starfleet officers had come to believe the logs of this event were fabricated and had little-to-no basis in reality. (NF - Prometheans novel: Martyr)


Related mediaEdit


Video releasesEdit


Episode imagesEdit

Adaptation imagesEdit



published order
Previous episode:
And the Children Shall Lead
TOS episode produced Next episode:
Is There in Truth No Beauty?
Previous episode:
Assignment: Earth
TOS episode aired Next episode:
The Enterprise Incident
Previous story:
first story
Star Trek 8
Next story:
The Enemy Within
chronological order
Previous Adventure:
Dreams of the Raven
Pocket Next Adventure:
How Much for Just the Planet?
Previous Adventure:
Dreams of the Raven
Voyages of the
USS Enterprise (NCC-1701)
(2264 to 2270)
Next Adventure:
How Much for Just the Planet?

External linksEdit

Community content is available under CC-BY-SA unless otherwise noted.