Cool Big Sis: To Eric and also Jenny in the first few seasons, until they liked the same guy.
Distressed Damsel: The fact that being in a car crash thanks to wolves roaming New York, being conned by her boyfriend, and her mother having her arrested for stealing a bracelet are not the best examples of why she fits this trope should tell you something.
Subverted. Serena made good grades her last two years of high school, and won admission to three Ivy League universities.
Easily Forgiven: Slightly subverted. She took Blair's boyfriend's virginity, then moved to Connecticut without telling Blair she was leaving, then ignored Blair's calls, texts and e-mails for a year even though she knew Blair's parents were getting a divorce (due to Blair's father leaving her mother for another man) and Blair's father was moving away to France. Blair did give her hell and humiliated her in public, but then forgave her after a few episodes. Not for the last time, either.
"I am not a stop along the way. I am a destination."
Serena's BFF (and occasional rival). The preppy queen of Constance Billard, always with a crew of minions around her. Ruthless and elitist yet very much a loving friend and girlfriend. Although if you ask Dan Humphrey she's a 95-pound, doe-eyed, bonmot-tossing, label-whoring package of girly evil.
Love Martyr: For Chuck Bass. Then in late season three she realises it's not healthy to love someone so much that you'd prostitute yourself for them and breaks up with him.
Then, in Season 5, she realizes she'll probably never get over him and decides she wants to be with him anyway. Ironically, by that time his Character Development has turned the trope around and he's been a Love Martyr for her for about two seasons.
"Dude. I’m Chuck Bass. Even Europeans must know what that means."
Serena's brother (through adoption) and Blair's main love interest. The richest character on the show and also the most ruthless. Spends most of his time brooding in fancy suits while sipping scotch and plotting somebody's downfall.
Karma Houdini: Though not as bad as most characters on the show. True he does a lot of bad things but he oftentimes gets his comeuppance, like for instance losing Blair multiple times due to his own schemes (which would be a aversion of this trope).
It's arguable whether this applies to him re: attempting to rape Serena and Jenny. The first example got him kneed in the crotch and the second got him punched in the face, however he never faces any legal repercussions.
Applying the trope in a more general sense for the character as a whole, he probably lands on the side of averting the trope. He does a lot of bad things, like all characters on the show, but he also ends up losing his father (only for said father to later return from the dead, take away the company Chuck has worked hard for and then try to kill him, loses his company on more than one occasion, gets conned by his uncle and a woman pretending to be his long lost mother, gets shot, has all his friends turn their backs on him, nearly dies in a car accident... Basically, Chuck may do more bad things than the other characters but he also suffers a lot more than the other characters, meaning karma might actually be working just fine in his case.
"Affairs with married people, love triangles... Just so happens everyone's problems are within my area of expertise."
The fourth member of the show's core four (aka the Non-Judging Breakfast Club). Chuck's best friend, Blair's former boyfriend and Serena's occasional love interest. Comes with a large dose of family drama, a fair dose of stupidity and dashing manbangs.
The Ditz: A very sweet guy but he can dumb as a box of hair.
The Drag-Along: Nate usually has to be forced or talked into joining the NJBC adventures. He becomes a lot more willing during season 6.
Dumbass No More: Usually the dimmest of the group, Nate's intelligence rises to average or above in the final season as he actively works to help his friends in their schemes. That doesn't stop him from following in his father's footsteps as far as business goes, though.
With Friends Like These...: Treats his best friend Chuck like crap most of the time. Though Chuck is often willing to respond in kind.
"We don’t have any servants here so if you see anybody else in the loft besides me, call the police. It’s not the chef."
Dan is the Brooklyn boy who falls in love with IT girl Serena van der Woodsen, only to find he doesn't exactly fit well in her world. By and by he becomes more adjusted, but he still thinks the world of the Upper East Side crowd is highly immoral. Dan is an aspiring writer who in the books writes delightfully awful poetry but in the TV series prefers short stories.
Adorkable: Especially in Season 1 when he's trying to fit in.
I Just Want to Be Special: Dan just wants to be part of the upper-class world but he is repeatedly reminded that it won't happen.
Informed Ability: We're told he's a really good writer and he managed to get published in the New Yorker. But when we actually get to see anything he's written it's merely okay. And the Charlie Trout thing was just narmy.
"Don't you read Gossip Girl? Extortion is what I do, all day."
Dan's younger sister who starts off idolizing Serena and wanting Blair's respect. Her innocence vanishes more and more each season and by now she could probably out-bitch Blair if she wanted to. Jenny's got a talent for designing and loves to make her own clothes.Hardly ever seen in season four, and with Taylor Momsen dropped from the regular cast (and her subsequent announcement she was quitting acting in favour of music) likely to not appear at all in season five.
Put on a Bus: Season 4 had her moving upstate with her mother, a character only seen briefly in season 1 and mostly unreferenced throughout most of the series. She returns briefly but is likely gone for good.
Real Life Writes the Plot - The change of Jenny's personality & personal style were all because of Taylor Momsen's sudden change in personal style. She was also writen off the first time to pursue her musical career then permanently so when she continued to clash with production.
"If Serena's indiscretions were as PG as Jenny's, I wouldn't have needed the botox."
Biological mother to Serena and Eric, adoptive mother to Chuck, stepmother to Dan and Jenny. Lily was much like her daughter Serena when she was younger, trying to break free from her strict mother's demands. As an adult she has been spending most of her time getting married and getting divorced. She can be very caring and loving when she wants to, but most of the time she's an absent parent.
"I promise to eat caviar without spitting it out in my napkin when we go to dinner at Mayor Bloomberg’s. As long as he knows when he comes to our house he’s eating my chili."
Dan and Jenny's father, and stepfather to Eric, Serena and Chuck. A former rock star (or at least pseudo-star) who had a love affair with Lily in his youth. Years later his son falls in love with Lily's daughter and eventually he and Lily find their way back to one another. Rufus is probably the most attentive parent on the show, although lately it seems he doesn't do much during the day.
Informed Ability: She's a good enough writer to get accepted at Tisch but we've never gotten to see anything she's written. She's also supposed to have a great talent for documentary film making but she seems to just walk around randomly with a camera...
Took a Level in Jerkass: In seasons one, two and three he was the only through-and-through decent character. In season four he plots to take Chuck and Blair down and hates on Chuck in favor of Jenny, even though Chuck has always treated Eric well and Jenny has thrown Eric under the bus countless times.
Title Drop: See Catch Phrase. (Exception: "The Revengers," which does not end with her saying "XO XO - Gossip Girl" due to Chuck and Blair running from the roof, having just watched the former's dad fall to his death.)
"KGB can't get me to talk. Chuck Bass has no chance."
Blair's nanny/maid/sidekick. Dorota is actually a Polish duchess but she moved to America to escape an unhappy marriage and began to work for the Waldorfs. In many ways the real mother figure in Blair's life and the person who does most of Blair's legwork for her.
Ascended Extra: Started out as a background character but evolved into Blair's eternal sidekick. Dorota got a backstory in the webisodes "Chasing Dorota" and had an entire episode revolve around her wedding day.
Older Sidekick: Blair's a teenager and while we haven't been given Dorota's exact age her actress is in her thirties. And Cyrus has confirmed that she practically raised Blair, meaning she ought to be at least ten years Blair's senior.
A former friend of Serena van der Woodsen and sworn enemy of Blair Waldorf, she is the series' most recurring antagonist.As it turns out during season 5 (major spoiler), she usurped Gossip Girl's identity.
Batman Gambit: In season 3's The Lost Boy, where she sends Blair a fake invitation to an elite society and uses a contact who works for someone Chuck is trying to impress in order to send the pair after the same photograph, thus bringing out both Blair and Chuck's competitive, self-serving sides and attempting to drive a wedge between the pair.
Blackmail: She blackmails Serena in season one; she uses her knowledge of Serena sort of, but not actually, killing a man to control her.
Evil Counterpart: She started out as what Serena could have become. In later seasons she seems to have become more of an Evil Counterpart to Blair around about the same time Blair became her main enemy.
Oh Crap: “You can tell Jesus that the bitch is back”. Cue epic Oh Crap look from Blair.
Put on a Bus: For almost a full season after she is sent to reform school in the season one finale. In fact, although she's a reccuring antagonist, she often appears only once in a while in each season for some episodes, and disappear as quickly as she arrived (after wreaking some havoc). Kind of a Zigzag Bus.