Brilliant, but Lazy: Invoked in the episode where the characters get their SAT scores back and Zack scores extremely high. The other characters realize out loud that although Zack's lazy, he's a lot smarter than he lets on. Zack himself tells them to keep it quiet, since he has "a reputation to look out for."
Chick Magnet: Is one of the most popular in Bayside. "Date Auction" is a good example of this.
Informed Attractiveness: Kelly was hot, no doubt, but few would argue that Lisa or Jessie were not just as hot. Within canon, however, Kelly was treated like a supermodel parading through the school.
Ivy League for Everyone: Probably the worst offender; 1100 on her SAT and from a cash strapped family yet made it into the same prestigious (if fictional) university as Zach (high SAT/upper middle-class family), Screech (Valedictorian), and Slater (sports scholarship).
Military Brat: Somewhat inverted as even though her father, Frank, worked at a defense plant, she never had to move around, unlike Slater.
New Powers as the Plot Demands: Played with, regarding her singing ability. In "Miss Bayside," she can't carry a tune. In the very next episode, "Jessie's Song," she (along with Jessie and Lisa) is noted to have excellent singing talent. In "The Glee Club," she's just as helpless as everyone in the glee club not named Violet, yet in "The Last Dance" and "Rockumentary" she's the only member of the gang's band who only sings (doing so angelically) and doesn't play an instrument.
Nice Girl: She's head cheerleader and the most popular girl in school but she's also the most sweet natured character in the show (and it isn't because she's spoiled sweet either because she's from a poor family).
The Fashionista: Throughout the series. Also, she apparently becomes one in the literal sense as an adult, as she gets accepted to a prestigious fashion institute at the end of high school.
Fashion Designer: In a final season episode she is applying for an internship at a clothing design studio and as a part of the application process she has to put on her own fashion show with her own designs and models. Kelly and Jessie are the models while Zak and Slater organize the event.
Spoiled Sweet: Had a sweet personality even though her family is well off.
Suspiciously Similar Substitute: Sort of. After Kelly and Jesse left the show, Lisa got a noticable boost in both popularity and brains so she could step into their shoes as the pretty and smart one to play against Tori's wild one. Lisa was always popular in canon, but after the other two left, it's like she became the only hot girl left at Bayside.
Kiddie Kid: He is the character with the least development, and is the goofiest to boot. It doesn't help that his actor is a few years younger than his costars, yet his character is the same age on the show.
Karma Houdini: Surprisingly with a lot of Zack's schemes, he is rarely directly punished for them, despite being Zack's unindicted co-conspirator.
Lovable Nerd: Was this initially, before his voice changed. He was such a cute, dorky little kid & far less annoying.
The Millstone: He's frequently roped into scams by his best friend, Zack. And, as a running gag, he often unwittingly sabotages them.
Mr. Fanservice: The show never missed an opportunity to show off his impressive physique.
Mr. Vice Guy: Was a good guy despite being a male chauvinist.
New Transfer Student: Technically. He transferred to Bayside at the very beginning of the series, so he's not any newer to the audience than the rest of the characters. However, to the characters on the show, he was "the new guy," and the first season kept emphasizing this.
The Complainer Is Always Wrong: Much of her activism is mostly Played for Laughs and ends up doing more harm than good. Save for one serious occasion when she and Zack try to stop an oil tycoon from turning Bayside into a disaster zone.
Out-of-Character Moment: Most people know that Mr. Belding is a very strict but a kindhearted person. However, in one particular episode, "The Yearbook", he was more than willing to restrain Zack while Slater was gonna punch him. Zack got out of it with his classic Time Out power, and boy did Mr. Belding learn the hard way that he can't be sadistic without consequences.
Reasonable Authority Figure: Even Zack occasionally admits that Mr. Belding is a lot more reasonable than he usually gives him credit for. During the graduation episode, Zack gives Belding a hug. In the "Wedding in Vegas" movie when Mr. Belding is a guest at Zack and Kelly's wedding, Zack finally admits that he appreciates Mr. Belding and says "You made high school challenging."
Worthy Opponent: Despite his Butt Monkey status, he's one of the few people who can keep up with Zack's schemes and even turn them against him on a regular basis. Zack even admitted that that Mr. Belding made things challenging for him.
Biker Babe: She showed up at Bayside riding a motorcycle.
Chuck Cunningham Syndrome: Kelly and Jessie disappear, Tori appears and takes their place for nine episodes, then disappears, Jessie and Kelly reappear and everything carries on as normal as if Tori never existed.
The Lad-ette: A tough, rebellious, jacket wearing, motorcycle-riding tomboy.
Glory Days: A former NFL player for the San Francisco 49ers, Mike often wistfully reminisces about his days as a football player, and clearly loves the sport. On one occasion, while complaining about a Jerkass from his old team, he admits that he's jealous, and says "He's getting paid millions to play a game that I would have been willing to play for free."
Landlord: OK, not actually a landlord, as the characters were living in a college dorm, but he was their Resident Advisor, so Landlord is probably the closest trope that fits.
The Unseen: For most of the series. Mr. Belding constantly talked about her, but we never actually met her until an episode during senior year.
Renaissance Man: Is in the glee club, is a science geek, and mentions taking a Spanish cooking class.
Jerk Jock: Sometimes. By the end though, he, Screech, and Big Pete have a "breakthrough" during Mr. Belding's bizarre group-psychotherapy session in gym class, and Ox ends up swearing off making fun of nerds again.