Lessek Prime was the prime planet in the Lessek system.

In 2378, The Doctor was coerced by Zet and Nar into disguising himself as Captain Kathryn Janeway in a plot to steal the USS Voyager's warp core. Suspecting something was amiss, Commander Chakotay tested "Janeway" by inventing a story about how she, as a lieutenant, had saved an away team on Lessek Prime in 2363 by disobeying her captain's orders. (VOY: "Renaissance Man")