10 Amazing Behind-The-Scenes Secrets From Star Trek: The Next Generation
4. Quark
It's well known now that the Ferengi were something of a failed experiment in The Next Generation. Initially pitched as the series primary recurring antagonists, audiences just found them way, way, way too stupid to take seriously and the producers were forced to go back to the drawing board after Season 1. It was here they came up with the Borg though so it all worked out well.
Regardless, the Ferengi were given ample screentime in that first season and were readily established as a major part of the Star Trek universe. Their first appearance, in The Last Outpost, was derided as a disaster by fans and producers alike, but it was notable for being the first appearance in Star Trek of... Quark.
Well, sort of. Although credited as Letek, one of the Ferengi away team is played by none other than Arman Shimmerman, the man who would go on to play the definitive representation of the species in Deep Space Nine. Canonically, this is not the same character, but Shimmerman himself has said that he considers the two parts the same and the events of this episode as an important part of Quark's backstory.