Member of the Earth Alliance Health Organization, and assigned as chief medical officer to the Excalibur.  She is concerned for her sister who remains on the plagued Earth.

Played by Marjean Holden, who appeared in Bill and Ted's Excellent Adventure, The Lost World, Speed 2 and Mortal Kombat: Annihilation.  She also appeared as an Earthforce officer in the telemovie A Call to Arms.

Xenoarchaeologist, linguinst, and member of Interplanetary Expeditions.  He represents IPX's ambition to "cash in" on any important technological discoveries made whilst in search of the virus cure.  While he is still fond of his ex-wife, Cynthia Allen, he is even more fond of their cat, Mr Kitty (The Rules of the Game).

Played by David Allan Brooks.

Following the death of his parents (both Techno-mages) in a passenger transport accident (The Long Road; see also the novel Invoking Darkness), the young Galen was raised and trained by his father's friend Elric (seen in The Geometry of Shadows), a member of the Techno-mage ruling Circle, on the planet Soom.  In preparation for his final training to become a mage, Galen discovers a destructive new spell, and is forbidden by the ruling Circle to cast it.  When he disobeys, he is almost cast out of the Order, but instead given a mission - to uncover proof that the Shadows are indeed returning to wage war upon the galaxy.  During this mission, he develops a relationship with fellow mage Isabelle - but she is killed, betrayed by three of their own kind (The Well of Forever, The Path of Sorrows, the novel Casting Shadows).  In his quest to avenge her, he discovers that Techno-mage technology is not all that it seems (Summoning Light).

In January 2259, as the Techno-mages flee the oncoming Shadow War, Galen saves Matthew Gideon from being stranded in space following the destruction of his ship (War Zone, The Path of Sorrows, Summoning Light).  He spends nearly two years in hiding with the Order of Techno-mages before the death of Elric at the hands of a fellow mage in November 2260 pushes him to leave once more and seek revenge on the Shadows and their allies, especially the rogue mages Eliar and Razeel, a mission that takes him to Z'ha'dum itself at the same time as Captain Sheridan.  There, he learns how to gain mastery of the tech and become united with it (Invoking Darkness).

Once more defying the Circle to break out of the hiding place, Galen sends warnings to Sheridan about the return of the Drakh (A Call to Arms) before joining Gideon aboard the Excalibur to find a cure for the Drakh virus (War Zone), in between helping Vir's resistance movement on Centauri Prime (the novel Armies of Light and Dark).

Played by Peter Woodward, son of British actor Edward Woodward who himself appeared in the episode The Long Road.

Captain of an explorer ship assigned to lead the Excalibur mission.  He met Galen nine years previously after he was stranded in space when his ship, the Cerberus, was destroyed (War Zone), in an accident involving a hybrid-Shadow vessel (The Path of Sorrows, the novel Summoning Light).  He also won a mysterious object called the Apocalypse Box in a game of cards (The Path of Sorrows) - gambling being one of his favourite past-times.  The Box provides him with pointers and information that helps influence his decisions regarding the Excalibur's mission (Racing the Night, The Memory of War).  Also on the mission, he rapidly forms a torrid romance with Babylon 5 commanding officer Captain Elizabeth Lochley.

Played by Gary Cole, who appeared as Lucas Buck in the TV series American Gothic, and as Mike Brady in the two Brady Bunch movies.

Second-in-command of the Excalibur, and also a telepath released back into society following the disbanding of Psi Corps after the Telepath War (in which he played a minor part in assisting the rogues (The Path of Sorrows)).

Played by Daniel Dae Kim, who appeared in the 1997 remake of The Jackal, the Star Trek: Voyager episode Blink of an Eye; and more recently as Wolfram & Hart lawyer Gavin Park in Angel.

Trained pilot originally assigned to Max Eilerson before being assigned to the Excalibur by Gideon (War Zone).  He used to be a priest for the Foundationist religion before some unexplained tragedy changed his faith (Ruling From the Tomb).

Played by Alex Mendoza.

After her homeworld, Zander Prime, was destroyed by a Shadow Planet Killer at the tail end of the Shadow War, Dureena believed herself to be the only surviving member of her race, and blamed Sheridan for failing to save her people.   Escaping the slave traders of Praxis 9 (The Memory of War), she joined the Thieves' Guild in order to survive, and was recruited by Galen to join Sheridan in fighting off the first of the Drakh attacks (A Call to Arms), before remaining aboard the Excalibur to help save Earth.

During her travels, she found a small colony of her people on a remote world, who are infected with the Drakh virus and are not expected to survive for longer than a year (Patterns of the Soul).

Played by Carrie Dobro, who appeared in Babylon 5 (Exogenesis, Racing Mars), and also in the short-lived children's SF series Hypernauts.