"Thank you, ambassador! I shall represent our people to the best of my ability."
"Just don't give away the homeworld."
- – Ko D'Ath and G'Kar during the Euphrates Treaty negotiations
Ko D'Ath was a Narn who briefly served as G'Kar's attaché.
In 2258 Ko D'Ath was G'Kar's first, albeit short-lived ambassadorial aide. She arrived on babylon 5 several hours earlier than G'Kar expected, having booked an early transport, eager to begin her assignment. Aggressive and very serious about her duties, she did not tolerate much foolishness. When Londo Mollari failed consistently to show up to negotiate the Euphrates Treaty, he eventually sent Vir Cotto to negotiate in his stead. G'Kar, insulted by the gesture, declared that Ko D'Ath would in turn operate in his place. Ko D'Ath is delighted about the opportunity, but G'Kar admonishes her with the same warning Londo gave Vir not to "give away the homeworld." 
Ko D'Ath was killed a short time later in what Ambassador G'Kar would describe as an "unfortunate airlock accident", necessitating her replacement by Diplomatic attaché Na'Toth the following week.
Behind the Scenes
Ko D'Ath, who was portrayed by Mary Woronov, was intended to be a regular character on the show, though ultimately Woronov could not cope with the extensive make-up prosthetics and would not wear the contact lenses (hence Ko D'Ath's atypically blue eyes), necessitating her character's replacement with a new attaché Na'Toth, after just a single appearance in "Born to the Purple".