Mrlsst was a planet located in the Tapani Sector's Freeworlds Region on the Shapani Bypass. It was the homeworld of the Mrlssi. It was the only planet in the sector with an indigenous alien race. It was a moist and humid world, with terrain dominated by marshes and sandy swamps. Nearly everywhere, one could find the towering greenstalk plants that grew all over the planet, except the poles.
A thick asteroid field surrounded the planet, which was used for raw materials and was the location of several research stations.
Thousands of years ago, the planet's continents were unstable, resulting in frequent groundquakes and tidal waves; the natives became used to losing possessions amidst such disasters, and came to appreciate knowledge as a result. The planet had grown much more stable by the time of the Galactic Civil War, but the tradition of learning endured among the Mrlssi.
The first contact between the Mrlssi and humans occurred 11,708 BBY. Mrlsst joined the Galactic Republic 6,997 BBY. Canny Mandary Bertar represented the planet in the Galactic Senate, and after the Republic was reorganized into the first Galactic Empire, the Imperial Senate.