In2261,theVorlonsjointheShadowWar,buttheirtacticsbecomeaconcernforthealliancewhentheVorlonsbegindestroyingentireplanetswhichtheydeemtohavebeen"influenced"bytheShadows.Disturbedbythisturnofevents,Babylon5recruitsseveralotherpowerfulandancientraces(theFirstOnes)totheircause,againstboththeShadowsandtheVorlons.CaptainJohnSheridanreturnstothestationafterescapingfromZ'ha'dum,butataprice:barringillnessorinjury,hehasonly20yearslefttolive.HeisaccompaniedbyamysteriousaliennamedLorienwhoclaimstobetheoldestsentientbeinginthegalaxy.  bbb
HoursbeforeSheridan'sreturn,Garibaldiisrescuedandreturnedtothestation,inratherdubiouscircumstances.HeismarkedlymoreparanoidandsuspiciousofotheralienracesandofSheridanthanhewasbefore.
CentauriEmperorCartagiaforgesarelationshipwiththeShadows.LondoMollariengineerstheassassinationofCartagiaandrepudiateshisagreementwiththeShadows.LondokillsMr.MordenanddestroystheShadowvesselsbasedontheCentaurihomeworld,inanattempttosavehisplanetfromdestructionbytheVorlons.Aidedbytheotherancientraces,andseveralyoungerones,SheridanluresboththeVorlonsandtheShadowsintoanimmensebattle,duringwhichtheVorlonsandShadowsrevealthattheyhavebeenleftasguardiansoftheyoungerraces,butduetophilosophicaldifferences,endedupusingthemaspawnsintheirendlesswarsthroughouttheages.Theyoungerracesrejecttheircontinuedinterference,andtheVorlonsandShadows,alongwiththeremainingFirstOnes,agreetodepartthegalaxyforever.
AftertheShadowsaredefeatedGaribaldileaveshispostassecuritychiefandworksonhisownasa"providerofinformation".HebeginsworkingforoneWilliamEdgars,aMarsTycoon,whoismarriedtoGaribaldi'sformerlove.WhileheworksevercloserwithEdgars,hebecomesincreasinglyaggressivetowardsSheridanandeventuallyleavesBabylon5.
MinbarisgrippedbyabriefcivilwarbetweentheWarriorandReligiouscastes.DelennsecretlymeetswithNeroonoftheWarriorcasteandconvinceshimthatneithersidecanbeallowedtowin.Shetellshimthatshewillundergoaritualwhereinshewillbewillingtosacrificeherself,butwillstoptheritualbeforesheactuallydies.WhenNeroonseesthatsheactuallyintendstogothroughtheentireritual,herescuesherandsacrificeshimselfinstead,declaringthat,althoughhewasbornWarrior,inhisheartheisReligious.
AspartoftheongoingconflictbetweenEarthandBabylon5,GaribaldieventuallybetraysSheridanandarrangeshiscaptureinordertogainEdgars'trustandlearnhisplans.GaribaldilaterlearnsthatEdgarscreatedavirusthatisdangeroustoonlytelepaths.Itisthenrevealed,thatGaribaldiwasactuallyabductedbythePsi-CorpsattheendofSeason3andre-programmedbyBestertoprovideinformationtohimattherighttime.BesterreleasesGaribaldiofhisprogramming,andallowshimtoremembereverythinghehasdonesincebeingkidnapped.Edgarsiskilledandhiswifedisappears,butisreunitedwithGaribaldiaftertheendofthewar.GaribaldihelpsfreeSheridanandreturnhimtothecampaigntofreeEarth.AnallianceledbyBabylon5freesEarthfromtotalitarianrulebyPresidentClarkinashortbutbloodywar.ThisculminatesinClark'ssuicideandtherestorationofdemocraticgovernment.Marsisgrantedfullindependence,andSheridanagreestoresignhiscommission.TheLeagueofNon-AlignedWorldsisdissolvedandreformedintotheInterstellarAlliance,withSheridanelectedasitsfirstPresidentandcontinuinghiscommandoftheRangers,whoaretoactasagalacticequivalentofUnitedNationspeacekeepers.
Intheseasonfinale,theeventsof100,500,1000,andonemillionyearsintothefutureareshown,depictingBabylon5'slastinginfluencethroughouthistory.Amongsttheeventsshownarethepoliticalaftermathofthe2261civilwar,asubsequentnuclearwaronEarthinvolvinganewtotalitariangovernmentintheyearAD2762,theresultingfallofEarthintoapre-industrialsociety,thelossandrestorationofhumanity'sknowledgeofspacetravel,andthefinalevolutionofmankindintoenergybeingssimilartotheVorlons,afterwhichEarth'ssungoesnova.
内尔·德贞,尼克·亨德里克斯,菲奥娜·多尔曼,安妮特·白兰特,安伯·阿迦,迈克尔·伯恩,Beth Cooke,约翰·康明斯,Zebb Dempster,安吉拉·格里芬,托尼·加德纳,Anita Harris,杰森·梅雷尔斯,安佳丽·莫辛德拉,Chu Omambala,伊莲·佩姬,马诺伊·阿南德,迈克尔·海登,乔·惠特利
内尔·德贞,尼克·亨德里克斯,菲奥娜·多尔曼
内尔·德贞,格威利姆·李,菲奥娜·多尔曼,曼金德·维尔克,海伦·巴克森代尔,阿拉斯泰尔·麦肯齐
内尔·德贞,格威利姆·李,菲奥娜·多尔曼,塔姆金·莫莉森,詹姆斯·莫瑞,汉娜·托茵东
内尔·德贞,格威利姆·李,菲奥娜·多尔曼,塔姆金·莫莉森,尤娜·斯塔布斯,乔治娅·泰勒
内尔·德贞,尼克·亨德里克斯,菲奥娜·多尔曼,安妮特·白兰特