Ulkesh, in the culture of the
Vorlon Empire was a subordinate to
Kosh Naranek, If Kosh could be described as a Gentle, curious
Vorlon, Ulkesh was the
harsh,
militant Vorlon.
From what we know of Ulkesh, he is slightly younger then Kosh, and probably old enough to know Valen, or even have met Valen when he arrived on the scene in the year 1250. Ulkesh probably fought with Valen in the last Shadow War and was entrusted (along with Kosh) to guide the younger races, as instructed by Valen's prophecies. (And it is very likely that both Kosh and Ulkesh knew that Valen was really a human from the future, whom they would both meet when Jeffrey Sinclair would exist 1000 years later.)
It is not known what Kosh or Ulkesh were doing after the Shadow War but they were not witnessed again, by the younger races, until after the Dilgar War, when they appeared to the Minbari Grey Council Leader Dukhat. They came, as prophesied by Valen to warn the Minbari of the increase of Shadow activity at Z'Ha'Dum. They also came with information, for Dukhat, to encourage him to ally with the humans (whom the Minbari Federation has not made First Contact with yet.)
However, before Dukhat could act on this information, he was killed in his First Contact with the humans when the EAS Prometheus fired on the Grey Council's Sharlin Class Warcruiser. Both Kosh and Ulkesh were now a mystery to the Minbari aboard, until Delenn discovered them, and the information was passed to her.
(cf. "In the Beginning")
After the
Earth-Minbari War was over,
Kosh, as instructed by
Valen went to
Babylon 5 to serve as the
Vorlon Ambassador and Ulkesh remained with the
Minbari and remained on
Minbar. From there, the two
Vorlons manipulated the two key races to mobilize against the Shadows, and they were able to train
Jeffrey Sinclair to one day become
Valen.
(cf. "War Without End, Part One")
Once
Kosh was killed in "
Interludes and Examinations", Ulkesh was quick to replace his fallen mentor. Ulkesh did not reveal his name, and spoke in equal riddles to Kosh,
"We are all Kosh".
(cf. "Walkabout")
However, the two Vorlon's styles quickly clashed, and without
Kosh's gentleness, Ulkesh was viewed as a tyrannical monster, which translated into a
Vorlon massacre of any worlds that aligned with the
Shadows. Which lead to an urging by
John Sheridan (and the help of the part of
Kosh that was living inside him) to attack, vanquish and eliminate Ulkesh.
(cf. "Falling Toward Apotheosis")
JMS has gone on to explain that the Two Vorlons were paired to balance each other out, that Ulkesh, thought militant, needed to be gentle, and Kosh, though gentle, needed to be more proactive and adversarial.
Ulkesh first appeared in the episode "War Without End, Part One"
Ulkesh, in the next episode, appeared as "Kosh" in "Walkabout"
Ulkesh was killed by Sheridan and Kosh in "Falling Toward Apotheosis"
Ulkesh was given his real name in the novel "To Dream in the City of Sorrows"
Ulkesh was shown in unison with Kosh in "In the Beginning"