Season 5: The Wheel of Fire
Kosh/ Minbari Assassin/ Sinclair/ G'Kar/ Sinclair/ Gen. Hague/ Londo/ Elric/ Sebastian/ ISN Reporter/ Sheridan/ Bester/ Sheridan/ Zathras/ Kosh/ Lorien/ Lorien/ Delenn/ Sheridan/ Sheridan/ Sheridan
(many thanks to Wikipedia)
In 2262, Earthforce Captain Elizabeth Lochley is appointed to command Babylon 5. The station grows in its role as a sanctuary for rogue telepaths running from the Psi Corps, resulting in a violent conflict. G'Kar, former Narn ambassador to Babylon 5, becomes a spiritual leader after a book was published that he wrote while incarcerated during the Narn-Centauri War. The Drakh, former allies of the Shadows who remained in the galaxy, take control of Regent Virini on Centauri Prime through a parasitic creature called a Keeper, then incite a war between the Centauri and the Interstellar Alliance, in order to isolate the Centauri from the Alliance, and gain a malleable homeworld for themselves.
Centauri Prime is consequently decimated by Narn and Drazi warships, and Londo Mollari becomes emperor, accepting a Drakh Keeper under threat of the complete nuclear destruction of the planet. Portions of the end of his reign are seen in various time-travel sequences throughout the series; one such sequence shows Mollari and former nemesis (and later friend) G'Kar dying at each other's throats in an act of mutual suicide. Vir Cotto, Mollari's loyal and more moral aide, succeeds him as emperor, free of Drakh influence. Sheridan and Delenn marry and move to Minbar, along with the headquarters of the Interstellar Alliance.
Twenty years later, on the verge of death, Sheridan takes one final trip to the now-obsolete Babylon 5 station before its decommissioning. Sheridan apparently dies, but is claimed by the First Ones, who invite him to join them on a journey beyond the rim of the galaxy. The Babylon 5 station is completely destroyed in a planned demolition shortly after Sheridan's departure, its existence no longer necessary as the Alliance has taken over its diplomatic purposes.
(Many thanks to Wikipedia and The Worlds of JMS)
President John Sheridan - Bruce Boxleitner
After returning to Babylon 5, President Sheridan began the process of leading the new Interstellar Alliance. The first years of the Alliance would bring about numerous problems that would shake the Alliance to its core. Sheridan had to work to keep the Alliance together, despite forces that were working to tear it apart. President Sheridan brought Captain Elizabeth Lochley to the station to take command. Even though Sheridan described her as Ivanova's replacement, she was really a replacement for the both of them. Lt. Corwin took over some of Ivanova's other duties. Sheridan gave her a free hand to run the station's affairs, reserving only the political course of the Alliance to himself.
Captain Elizabeth Lochley - Tracy Scoggins
Dr. Stephen Franklin - Richard Biggs
Zack Allan - Jeff Conaway
Allan was the second aide to B5 Chief of Security Michael Garibaldi from 2259-2261. Following Garibaldi's resignation as chief of security in season 4, Allan was appointed Chief of Security. He held the position for many years; except for a brief stint back on Earth, he remained there until the station was decommissioned in 2281. Because of this, he was the only one not to receive his invitation to Sheridan's farewell party in Sleeping in Light, though Allan would still meet Sheridan one more time as Sheridan took one last walk through the station. In Sleeping in Light, he walked with a noticeable limp, which has never been explained on screen. In the voiceover commentary of the episode, series creator J. Michael Straczynski explained that Zack was involved in heroic activity and lost his leg. Later in the episode, after the aged and abandoned Babylon 5 was destroyed and the Drakh influence on Centauri Prime was exposed and eliminated, Zack joined the Rangers and became Centauri Emperor Vir Cotto's assistant and (presumably) a direct liaison between the Emperor and the Interstellar Alliance.
During their return trip to Babylon 5 over the turn of the year to 2262, Delenn married John Sheridan in a private ceremony.Although Delenn was still Anla'shok Na of the Rangers, she deferred most of the day-to-day operations to others. However, she still had input. After returning to Babylon 5, Delenn discovered that she was pregnant. The only people more surprised than her were John Sheridan and Dr. Franklin. Delenn traveled to Minbar to oversee the final preparations of the new Interstellar Alliance headquarters at Tuzanor, the traditional home of the Rangers. She returned to Babylon 5 to collect her husband and belongings when the work was complete. When Delenn and Sheridan arrived on Minbar, Emperor Londo Mollari was waiting for them. He gave them a Centauri urn as a gift for their unborn child, instructing them to give it to him on his sixteenth birthday. During his visit, Delenn barely caught a brief glimpse of his keeper, but she didn't understand its significance. In December 2262, Delenn gave birth to a son named David.
Lennier did not act on his feelings due to her involvement with John Sheridan. Lennier did confess his feelings to her when he and Delenn were both trapped in hyperspace facing death, but Delenn, who had long known of his feelings for her, feigned that she hadn't heard his confession in order to spare him embarrassment.
His popularity was creating political pressure on the restored Kha'Ri as well, who finally insisted that he either come home to rule or publicly give them his blessing. The last straw was when he was forced to bluntly rebuke a particularly obnoxious would-be worshipper and that offended admirer attempted to assassinate him in retaliation, but ended up severely wounding Garibaldi's fiancée instead. G'Kar decided to leave Babylon 5 and explore the galaxy, knowing that he could do no more for his people there and that to stay would only cause more unrest. He appointed Ta'Lon as his successor. G'Kar would later return to Babylon 5 at least once more for a diplomatic conference.
Na'Toth - Julie Caitlin Brown
Londo Mollari - Peter Jurasik
Following the galactic war with the Shadows, Mollari eventually rises to Emperor of the Centauri Republic, taking the title Emperor Mollari II as another member of his family had been Emperor in the past. One of his first acts as the new Emperor was to name Vir Cotto as his replacement on Babylon 5, a job not highly prized because of the earlier Centauri conquest of Narn, though Londo knew that Vir would fulfill the job dutifully, even if some of the other ambassadors distrusted him. At the end of the fifth season, it was revealed that the Drakh had manipulated the Interstellar Alliance into attacking the Centauri Homeworld. The Drakh decided they needed Londo to be Emperor. The Regent, Virini, died when his keeper was removed, and another keeper was attached to Londo. For the next 15 years, Londo reigned as Emperor. Londo soon learned that alcohol would put the Keeper to sleep, and would allow him a few minutes of freedom.
Vir Cotto - Stephen Furst
Following the Shadow War, Vir returned to Babylon 5. For the next two years he continued to act as Mollari's assistant, and as a representative of the Centauri to Babylon 5 when Mollari was back on Centauri Prime. When Mollari ascended to the throne as Emperor, he named Vir as the Ambassador to Babylon 5 (now an important position). With the death of Emperor Mollari at the hands of G'Kar 15 years later, Vir killed Mollari's Keeper. After being approached by several Drakhs, he managed to escape from the throne room by jumping out the throne room window on to a waiting shuttle. From there Vir went to the Minbari homeworld. The remaining heads of the Centauri houses met him there. He was able to persuade the nobles into recognizing his claim as Emperor.
Lyta Alexander - Patricia Tallman
In early 2262, Alexander became romantically involved with Byron, the leader of a colony of rogue telepaths offered sanctuary aboard Babylon 5. Her contact, and sexual relationship, with Byron revealed to the telepaths that they had been created by the Vorlons as weapons for their war with the Shadows. This revelation directly lead to Byron's disastrous confrontation with the Interstellar Alliance. Although Byron eventually committed suicide rather than be captured by the Psi Corps, Alexander was inspired by his cause to create a homeworld for telepaths, and became the leader of a movement sponsoring violent resistance against the Corps.
She was eventually arrested aboard Babylon 5 for supporting terrorism by John Sheridan (whose contact with Vorlons gave him immunity to her Vorlon-enhanced telepathic abilities) in late 2262. Alexander then struck a deal with Michael Garibaldi: He would use his contacts, gained both when he was the Head of Covert Intelligence for the Interstellar Alliance, and those from his current position as the head of Edgars Industries, to help her avoid prosecution, as well as provide funding for her cause. In return, Lyta would remove a telepathic block placed in his mind by Alfred Bester. Former Narn Ambassador G'Kar was leaving Babylon 5 at the same time, and took her with him on a mission of exploration.
Byron - Robin Atkin Downes
Byron Gordon is introduced to Babylon 5 in the season 5 episode No Compromises as a strong telepath (P12 rating). Byron is shown arriving on the Babylon 5 station with a large contingent of rogue telepaths early in the year 2261. At this stage Byron is portrayed as a Gandhi-like figure; a leader of telepaths who seeks freedom from the Psi Corps and from mundanes, but that will only do so through non-violent means. In The Paragon of Animals, Byron helps the new Interstellar Alliance by revealing treachery by the Drazi against the Enphili. John Sheridan offers Byron and his telepaths political asylum at Babylon 5. They are allowed to establish a small colony in Brown 3.
Lorien - Wayne Alexander
Lorien reappears a last time, in 2281, when Sheridan returns to Coriana 6 during the last hours of his life, as he was enjoined by Kosh to do. When he returns, he initiates contact with Sheridan asking four key questions:
Who are you? (The Vorlon Question)
What do you want? (The Shadow Question)
Why are you here? (Lorien's Question)
Where are you going? (The Final Question)
Regent Virini - Damian London
After the assassination of Cartagia in The Long Night, Prime Minister Mollari informs him that he has been appointed Regent to the throne until the Centaurum clearly determine how to fill the vacuum of power in Epiphanies. However, by the end of Epiphanies Virini came under the control of the Drakh, whos sought revenge upon the Centauri Republic for their part in the Shadow War and plotted the destruction of Centauri Prime.
In the episode, The Fall of Centauri Prime, the Regent introduces Mollari to a Drakh. The Drakh explains that they were servants of the Shadows and they want revenge by isolating the Centauri. If Londo will not agree to serve them, the Drakh threatens to detonate fusion bombs all over the planet killing millions. Londo agrees, and the keeper leaves the Regent who then dies in Londo's arms.