Trefolg was a Federation planet located near the Romulan Neutral Zone.

Trefolg was one of the Federation's closest colonies to the Neutral Zone. It was equipped with high-powered subspace radio equipment to account for its distance from Federation support. Trefolg's governor in 2269 was Lerak Kepac, around which time the colony was suffering from a deficiency in refined, alloyed metal.

Also in 2269, members of the United Expansionist Party acquired a starship on Trefolg and planned an incursion into the Neutral Zone to spark a conflict between the United Federation of Planets and the Romulan Star Empire. The conspirators were captured by colonial authorities and transferred to Starfleet custody aboard the USS Enterprise. (TOS novel: The Trellisane Confrontation)

planets visited by the USS Enterprise (NCC-1701) during Captain Kirk's initial five-year mission (2265-2270)
various Aprilia IIICaporyGarrusRheelTriangularis III
2265 EarthDraxis IITallyGamma Alpha VPollux IIStarbase 8 planetSector Vega 6 planetM-155Archernar IVDimorusMandylion VTendar IVMestikoAlpha Ortelina VIIArronus VIIAldebaran IIIDelta Vega IStarbase 12VelluriusEarthGlobular planetNorusJunkyard planetPalnak's planetSantarNova XIIIZeltokKorakthe Traveler's homeworldDukarOrthooAlgenib II
2266 Crucial-3VultraRobots' planetAngomaMantis planetNuofoStaiVrexBalant planetZargotColtacRigel XIIAlfa 177M-113Psi 2000Tlaoli IVSkurSelkyeTaragonAlpha 332Ynobe IIEcnalRayloNorigaAlpha Proxima IIKynardiArgylusOminnusEarthK-GSeggorForniaAngiraBeta IINeesanKujalLunaBwujaFayoHerculaEarthKibo/NdoraNrakaAlpha 23-COordonMobitaJodarrQuodarZartaFloe IMetamorphaInicrustMortiTerrellian IIVoodoo planetRiza homeworldMila XaKrugar III remnantQuaraxusArimaMazdaNumero UnoBeta CarinaeExo III1324-IV7348-IITantalus VMiri's homeworldPlanet QBenecia
2267 Taurus IIMakus IIIXimega IIHydra Epsilon IIIPerseus Arm planetoidYkoTenkaraSalvumGrotusVaranu planetYkoTalos IVTektonRifas-LAmusement Park planetHeitius VIICentaurus VFomalhaut VEmben IIICynur IVTyrtaeus IIGothosBeta VITheta VIIRamedes IIICestus IIIMetron planetAlvaLazarus's planetGalaxy Zekbran planetCygnet XIVEarthCanaraBeta IIIDraqqanaIach'tu PrimeEminiar VIICeti Alpha VGamma 400VartaxDak-AlphaTharkMorkolTimshelOmicron Ceti IIIJanus VI7348-IIChandra IVOrganiaAngrenaYkoEarth Colony IIGatewayEarthDenevaJanvarZentarZettinDiad II • "the Frontier" • ModalaLadoGamma XaridianElsinor H-25Starbase 10Beta Mariotia IIIVega IIITondusTekkorCarnakPyris VIIEarthPentam VGamma Canaris NVandros VIINukoleeStyraLurotaOorego IVGiant Brain asteroidOtari IIGatewayIsis IIINot EdenMaaba S'JaCapella IVPollux IVVulcanMestikoNadorTactis IIBeta Nirobi IIPhygma IVOutpost Omega-70Tau Gamma IVM-370Argelius IIMerope IVMalurEulusDonico IIGamma Trianguli VIMasabaLekythosTyrtaeus IIShroud IVHalkaIxtoldeGamma Hydra IVCalydonBelmara IVTuran Tot Narut's planetGamma Canaris NTaunusPlanet 656Beton IIISklurrKarrGraktanPlixesAndriusMuddEarthAneher IIWezonvuNalaingMagna RomaBavaryaNeolithiaMythraRimilliaBabelGamma Canaris NVulcanNisusCertaxNarnel's WorldNGC 667Neural
2268 Fornax IIGamma IITriskelionRudimonArgus XTycho IVCentaurusUsildeTheta VIISigni BetaTautee systemVulcanBeta Canzandia IIIMevinnaSigma Iotia IIXanviaXoxxaInquisitor planetBeta ReticuliDelta VegaNalogen IVDelta VegaDelta Canaris IVAlnath IIAmmdonArretEkosEeiauoSivaoKahlessOmega IVEarthTheta Kiokis IIElasTroyiusElethiaAlsandKosTau Delta IXAmerindStarbase 14 planetAndru 4/6Tranquility VIIMinos VEarthExo IIIT'nufoMinos VEando 375Wrigley's Pleasure PlanetExo IIITortuga VITaos IVTriacusMarcos XIIWokkle IIICawley IVMakon IIIKalaLowariaDreamers' planetSigma Draconis VIMoauvPomplanceRibol IIMarpapluDireidiMedusaElcidar Beta IIIMinara IIOctavius IVBeta CabriniPegasus IVCareta IVBeta XII-APlatoniusIzellEarthScalosM-317Beta Aurigae IIISanoora host planetRhinegeltKalandan outpostBrellian IVPrastorDistrelTttnicktttnorAriannusCheronElba IISanctuaryGideonTau Omega IVTau Omega IIIKolya
2269 Memory AlphaMerak IIArdanaPollux VAvalonBalkos IIINova Atar IIITarnak IIMeta IVVesbiusJanus VIPollux IILeora IVBeta Niobe IIIMygdalus IIIWaasertlaCentaurusRaga's PlanetEdenTheta Tau VHolberg 917GLothorTau Beta IVExcalbiaSarpeidonCamus IIDuwamishEphrata IVSigma Niobe IIGatewayKrasni's FollyVestalanMaltos IVOrganiaKyrosNestaAnomalyAcademyYkoArachnaeBabelEpsilon Delta IVHeartlandMemory PrimeTalin IVWeb of WorldsSyhaar PrimeGatewayMantillesValeriaTaurus IIKinshasaAmusement Park planetMotherlodeMegas-TuTerratinSherman's PlanetVerdanisThe StrandAarak IIIPhi XIUr homeworldVidenGobi IIIPacificaGralafiLoren VArgoWaycrossDengella IIPerryDelta Gamma IVTrefolgLloyd Zeta-9Sigma Iotia IIHesperides II'QosCirce VAndoriaTrellisaneBeta CastelliHoloxBoaco VIJuram VVancadiaChyrellkaVeletus VPatria IPelos
2270 Janus VIPhylos IIVedala asteroidDramiaDramia IIArretLactra VIIBoqu IIDelta Theta IIIPandroBriamosYkoBelarius IVVelat Nol/R-836 IIGelladorn/R-775 IDT-262Belarius IVCenotaphEmilla IIVehtora IVAnabarra colonyN'caiMuldoonCoridan IIIAkladiMuddKubanSaraiStarbase 7 planetStella Mudd's planetMuddTaygeta VOkeanosBeta Omicron Delta IIIYoondriGatewayZeta GibraltarAndrosYusubArtemys 314KwettirPolymax VIIIHollow PlanetEarth (alternate)GatewaySycoraxBira IIINjuraOmne's planetVoranRazarMercanAleriadAritaniYalboVulcanHoshan planetsTanisAragos planetAleph PrimeAleph IIIAntos IVTakoi homeworldEarthDenebiaVeneu IIGribbin IIKlondike VIIsitra ZeroPelosArchernar IVTalos IVPillagra/R-855EarthStarbase 12Tomarii
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