A variety of Leviathans seen in the comic issue "Crawling From the Wreckage"
Leviathans are large, living ships on Farscape. The most prominent individual on the series is Moya. They are noted for their ability to Starburst — a method of faster-than-light travel.
Leviathans are sentient biomechanoids, consisting of organic and inorganic materials. They can feel pain and give birth. Created by the Builders, Leviathans are now bred by the Peacekeepers to be used as transport. When fitted with a control collar, Leviathans and their Pilots symbionts can't do anything without PK authorization.
According to "Vitas Mortis," Leviathans live for about 300 hundred years, significantly less than their bonded Pilots. Their amnexus fluid is functionally analogous to blood in other organisms (and it's used by crew members to wash laundry). They are primarily a bronze color, although the Farscape comic book introduced blue, green, pink, and purple Leviathans.
Internally, Leviathans contain a number of spaces for their crew members, including living quarters, kitchens, workspaces, and hangars. As Leviathans grow, these spaces do too. Leviathans have an internal atmosphere for their passengers, and they create DRDs that perform any task required of them around the ship.
Personality-wise, Leviathans are gentle giants. One exception, however, was seen in the episode "Dog with Two Bones," in which a rogue Leviathan attacked Moya in sacred Leviathan burial space.