Ulkesh is representative of the militant element of Vorlon society. Presumably, this is the dominant group within the Empire.
After the death of Kosh, Ulkesh arrived on Babylon 5 to replace him. Among his duties was to find if a piece of Kosh's soul existed, and, if it did, to return it to the Vorlon Homeworld for unknown purposes. Upon his arrival to the earther station, Ulkesh assumed Kosh's identity and to outsiders it only appeared that Kosh had bought a new encounter suit. His first order of business was to confirm what the Empire knew: Kosh was assassinated by the Shadows. That a human agent was with them was somewhat surprising.
The failure of Kosh's pet human, Lyta Alexander, was expected. Since she did not have a piece of Kosh within her when the old ambassador died, the usual retribition was called for. However, she might be useful in tracking down a hoped for piece of Kosh, hidden within an unsuspecting person near the death scene.
After Lyta assisted the Army of Light to deafeat a Shadow ship, she returned with news that Kosh may yet live. This vital piece of information was put on hold until Captain Sheridan returned from the dead. When the Vorlon Madness erupted (destroyijng world after world because of their contact with the Shadows), Ulkesh became a liability to those on Babylon 5. Captain Sheridan ordered his assassination. Only through the intervention of the remains of Kosh (augmented by Sheridanís and Lorienís lifeforce) was Ulkesh silenced.
[Voiced by Aardwright Chamberlain]