One of the things Star Trek is known most for is its ever-expanding universe, fleshed out through the various additions to the franchise over the years. The franchise has created and portrayed a multitude of different planets and alien races, from the mighty, ever-changing Klingon empire to the galaxy-dominating, ever nefarious Borg. Alongside these returning species, there is a whole host of "throw-away" species, those which appear for a single episode or plot and then are never seen again. Voyager did this a lot as the crew traveled from the Delta quadrant back home (one of the multiple reasons fans criticize the series), but there have been some wonderfully memorable throw-away alien races. The most notable of all are perhaps the Tribbles.