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.
本·巴恩斯,玛丽-露易丝·帕克,乔·弗瑞曼,朱利安·瑞钦斯,汉娜·高威,罗伯特·乔伊,丹·贝尔尼,马丁·罗奇
哈维尔·古铁雷斯,特里斯坦·乌罗阿,坎德拉·佩尼亚,艾丽西娅·博拉切罗,弗兰塞斯克·奥雷利亚,Tito Asorey,里卡多·德巴雷罗,Vianessa Castaños,Felice
托比·琼斯,莫妮卡·杜兰,茱莉‧赫斯姆德哈尔格,阿历克斯·杰宁斯,伊恩·哈特,莉娅·威廉姆斯,威尔·梅勒,克莱尔·加尔布雷斯,邵恩·杜里,阿米特·沙阿,莱斯利·尼科尔,亚当·詹姆斯,凯瑟琳·凯丽
诺尔·费丁,休·博纳维尔,艾丽·怀特,马克·伍顿,德维恩·博阿奇,塔姆辛·格雷格,阿西姆·乔杜里,多莉·韦尔斯,乔·威金森,杰弗里·麦吉弗伦,迈克尔 菲尔丁,塞缪尔·利基,凯丽·弗莱赫蒂,马克·希普
嘉科莫·吉安尼欧缇,莫妮卡·格瑞托
珊·布鲁克,马丁·麦凯恩,凯瑟琳·德夫林,内森·布兰尼夫,汉娜·麦克莱恩,乔安妮·克劳福德,安迪·奥修,弗兰克·布莱克,帕蒂·杰金斯,德斯蒙德·伊斯特伍德,安德里亚·厄文,奥依申·麦卡恩,阿比盖尔·麦吉本,谢默斯·奥哈拉,莎娜·凯斯雷克,克雷格·麦金莱,丹·戈登