Star Trek has created many great alien races and many great alien characters from those species. They've spanned the gamut, from raging space warriors to cybernetic zombies that just want to consume. Yet, the one alien race that seems to have not only survived all these years but dramatically changed what they were going to be portrayed as was the Ferengi. The Ferengi were meant to be villains of the highest orders for the new crew of Star Trek: The Next Generation.
Almost more like a sect of vampires meets locus, they were meant to be the big bad of the The Next Generation but their debut failed so hard that no one could take them seriously. So they went back to the creators' room for some more tweaking. The race of aliens would go on to appear across the first five and a half seasons of The Next Generation, but they were never embraced as a creators' likable alien and many fans would end up skipping Ferengi-centric episodes.
But when Deep Space Nine launched, they brought back one of the original actors of the Ferengi race, Armin Shimerman. He played Letek in the first Ferengi-centric episode, "The Last Outpost" and has since apoloized for his performance in the episode, but he'd make good, bringing to life not only the most popular Ferengi in the franchise's history but one of the most beloved characters in all of Star Trek's canon.
Quark became a driving point on Deep Space Nine, the series that followed The Next Generation. Quark was a devious and shrewd businessman, who wouldn't think twice about rigging things slightly to improve his bottom line. His quick wit, genuine charm, and ability to play a villain or a hero depending on what was called for made him one of the most cherished and in-demand characters.
So much so that Shimerman, dressed as Quark would do guest spots on talk shows to hype up the series. He was the face of DS9 in the eyes of many fans, and after his creation, the Ferengi were never again seen as such a laughing stock, even if they were used more often than not as comedy relief.
Quark elevated the Ferengi more so than any one character would or could elevate an entire species on the show. Even defining characters like Spock with the Vulcans or Worf with the Klingons didn't have to do nearly as much heavy lifting as Quark did for the franchise.