Kurl was a formerly inhabited planet in the Kurlan system, many light years outside Federation territory. Kurl was home to the extinct Kurlan civilization, whose remains were of great archaeological interest. In the 24th century, the only planet near Kurl capable of supporting life was Loren III.
Federation archaeologist Galen completed a study of Kurlan artifacts in the 2360s. He returned to Kurl briefly in 2369 on his way to Loren III, during which he obtained a Kurlan naiskos for his former student Jean-Luc Picard. (TNG: "The Chase")
This planet was only mentioned in dialogue.
In the novel Worlds of Star Trek: Deep Space Nine, Volume Two, it was revealed that the parasitic beings from TNG: "Conspiracy" were genetically created from Trill symbionts in an ancient Trill colony on Kurl.