Ensemble Darkhorse/Tabletop Games

Examples of s in include:

Board Games

 * Kharn the Betrayer of Warhammer 40,000 has been embraced by the fandom, declaring him to be a pretty fun guy to be around and focusing on him to the exclusion of all other Chaos characters. It helps that he has a highly exploitable battle cry: ""
 * A Downplayed version is the Khornate Daemon Prince named Doombreed. He has a surprising number of references in the background of the game (approximately four, compared to the number of one-shot characters given a single paragraph), and he has become something of a Mauve Shirt in the background and on /tg/. It's speculated that he was Genghis Khan before, and that everything from his daemonic mount to his fu manchu mustache is on fire.

Card Games

 * Hans appeared exactly once on a single card in Magic: The Gathering, and never anywhere else, but the flavor text was popular enough that he got multiple references later on including a short story in the anthology Monsters of Magic (called "Ach! Hans, Run!"). Arguably, Norin the Wary similarly qualifies, having been elevated from the voice of cowardice on a handful of cards' flavor text to eventually receiving his own (also cowardly) creature card.
 * There's also Ib Halfheart, Goblin Tactician and, more famously, Jaya Ballard, Task Mage. Jaya Ballard's card has been known to win "best flavour text" votes on fan sites despite the card not actually having any flavour text (she supplies a solid number of fan favourite flavour text quotes on other cards).
 * In the Legend of the Five Rings CCG, Toku was originally an unaligned, free card with no abilities and no use other than being fed to demons. Fans enjoyed the idea of Toku so much that they started the "Toku for Emperor" movement, attempting to influence the game's interactive storyline. As a result, Toku became a major player in the game's storyline, going from a peasant who stole a dead samurai's sword to a real samurai, friend of the Emperor, Captain of the Imperial Guard, founder of a Clan, and (posthumously) a minor deity.

Tabletop RPGs

 * Dungeons & Dragons has a few examples. Inspired greatly by the example of Drizzt above, drow are a perennial favorite as Player Characters despite the race originally being Exclusively Evil. Future splatbooks expanded greatly on drow culture and options for drow players. They're even included as a PC race in the Fourth Edition Forgotten Realms setting.
 * This is lampooned in the webcomic Order of the Stick, where Nale's "Linear Guild" includes a Drow whose presence prompts the heroes to question, "Aren't Dark Elves evil?" Nale "explains" that that was before they were a player-character race; "The race now consists of nothing but Chaotic Good rebels struggling to throw off the reputation of their Evil brethren." "I thought you said they were all Chaotic Good?" "Details."
 * Another surprisingly popular race is kobolds, of all things. Despite their status as first-level Cannon Fodder (though their affinity for traps can make them more dangerous than you'd think), they've gotten a great deal of expansion in various splatbooks, including the 3.5 Edition Races Of The Dragon. One of the more infamous Game Breaker builds for the edition, "Pun-Pun", is a kobold.
 * It's kind of helped that the kobolds have been the setting's Butt Monkeys for so long that they've pretty much run all the way around on the opposite end of the sympathy scale to become woobies in their own right. Plus, nothing feels more satisfying than bringing down the BBEG with a small, scrawny lizard normally considered a CR of 1/6.
 * There is also a sort of Ugly Cute factor playing.
 * Which leads to then becoming utter badass Commandos.
 * Possibly based on this utterly brilliant session report.
 * The Tome of Magic Binder class is surprisingly popular considering the other 2/3s of Tome of Magic are the mechanically unplayable Truenamer and the mechanically odd Shadowcaster.
 * In a similar vein, "Complete Psionic" is widely panned as the worst of the "Completes" line released for 3.5. However, one class in the book (the Ardent) is acclaimed for its balanced play, appealing flavor and unique approach to psionics. The Ardent would eventually be adapted to 4th Edition as a psionic class.
 * Eberron gave D&D one of the more popular new races - The Warforged. Basically, they're Magitek Mechanical Lifeforms, and they've been generally well received by the D&D community. Even on /tg/, Warforged are generally quite popular. It's probably because, well, robots are just plain cool. As a matter of fact, Wizards of the Coast recently put up a free supplement for 4E Warforged, making them Canon Immigrants.
 * The Shifters were popular enough to make it into the fourth edition, as well; there is some Internet Backdraft among furry bashers, though.
 * If it's possible for a single game in a gameline to be an Ensemble Darkhorse, Changeling: The Lost from the New World of Darkness probably grabs the title.
 * To elaborate, Changeling was one of the limited series NWOD games White Wolf release, only meant to have the main source book and five supplements. From the get go the game was at a disadvantage; not only was it contending with Vampire: The Requiem, which was undisputedly the most popular NWOD game at the time, but it also was the revamped version of Changeling: The Dreaming, one of the least fondly remembered games of the OWOD. Combine that with the fact its subject matter (Fairies) lacked the universal appeal that, say, vampires and werewolves had, and it didn't bode well. However, when it came out sales peaked and the internet was filled with adoration and acclaim for the game and its setting. Sooon the Changeling fanbase was one of the biggest in the community and rivaled Vampire on fans and players. This huge influx of interest got the series three extra books and several more PDFs added to the line, making it one of the stand out titles of the NWOD.
 * In a similarly unusual turn of events, a piece of prose from the core rulebook of the New World of Darkness, "Voice of the Angel," has merited a stunning number of references throughout the line, up to and including the finale of a sample story in Saturnine Night and a new covenant in Danse Macabre.

Other Games

 * Rock-Paper-Scissors: Good, old rock, ain't nothing that can beat that.