After losing his wife and daughter, Sarah, in a terrorist attack destroying their passenger ship at the Io jumpgate, archaeolinguist Morden was assigned aboard the Icarus expedition, where he made friends with Anna Sheridan.  When the doomed expedition awoke the Shadows on Z'ha'dum, he was recruited to serve the Shadows as a representative (In the Shadow of Z'ha'dum, the novel The Shadow Within).  He first appeared on Babylon 5 to determine which of the major races the Shadows would find the most productive (Signs and Portents), and thereafter maintaining contact with Centauri Ambassador Londo Mollari (Chrysalis, Revelations, In the Shadow of Z'ha'dum).  He also infiltrates the Techno-mage order to try and recruit them as allies (the novel Casting Shadows).

After Londo decides to be rid of him (Matters of Honor), Morden took up contact instead with Lord Refa until Londo intervenes (Ceremonies of Light and Dark), whereby he conspired to bring Londo back into the fold and manages to take out the Vorlon Ambassador Kosh along the way (Interludes and Examinations).

He was also involved with Earth Vice-President Clark in the assassination of President Santiago (Chrysalis, Voices of Authority), and subsequently represented the Shadows during Clark's presidency (Matters of Honor).  He met Sheridan on Z'ha'dum (Z'ha'dum; see also the novel Invoking Darkness), survived the subsequent explosion (The Hour of the Wolf), and represented the Shadows on Centauri Prime (Falling Toward Apotheosis) before Londo cut his head off and stuck it on a pike (Into the Fire), as per Vir's wishes (In the Shadow of Z'ha'dum).

He returned to visit Lennier during the Brakiri Day of the Dead ritual (Day of the Dead).

Played by Ed Wasser, who had a minor role in the pilot episode The Gathering.