Nikki J. Maxwell
The protagonist of the story, an unpopular and utterly unlucky teenage schoolgirl who narrates her wacky daily life, usually on the topics of her family, her schooling, her crush, and other exotic events.
- Adorkable: She considers herself to be both dorky and cute.
- Animesque: The Dork Dairies have anime drawing style supposedly because Nikki's an artist.
- Bad Liar: Every time she has to think of a lie on the spot, chances are she'll come up with something completely ridiculous, such as having to take care of a sick unicorn. Some people believe her anyway.
- Badly Battered Babysitter: Whenever she has to babysit Brianna, she ends up this way. Something always ends up burned, broken or ruined (including Nikki's reputation).
- Bratty Teenage Daughter: She doesn't really share the desire to bond with her family and writes about how much they annoy her in the diaries.
- Buffy Speak: Doesn't always know the correct word for something and ends up using "thingy", like calling a fake wireless headset (made out of a hearing aid) a "faux cell phone thingy".
- Butt-Monkey: A lot of bad things tend to happen to Nikki in each book on an almost every page basis.
- Cool Loser: Despite being a cute, friendly, and optimistic girl, she is the most unpopular student at her school.
- Deadpan Snarker: Her comebacks to MacKenzie definitely qualify, and she shows shades of this around others too.
- Does Not Like Spam: She hates pickles.
- Drama Queen: She has a tendency to freak out over minor problems and panic too much. Her lively imagination doesn't help either.
- Eating Lunch Alone: She's a loner and is seen eating alone at school before meeting Zoey and Chloe in gym class.
- Fatal Flaw: Pretty much the flaws any teenage girl would have. She is insecure about her appearance and attention she gets from the people around her. She is also shy, overdramatic, vulnerable, and quite sensitive about many things. She also has a tendency to believe that she doesn't need, or rather can't get, help or support from others so she spends a good majority of the books struggling alone.
- First-Person Smartass: Prone to snarky remarks, but she rarely (if ever) says them out loud.
- Foolish Sibling, Responsible Sibling: The Responsible to Brianna's Foolish
- Hair-Trigger Temper: The tone in which she writes her dairies is quite angry. She also panics very easily.
- Hypocritical Humor: At the very beginning of the first book she swears she'll never write in her diary again. Cut to her next entry two days later.
- Jerk with a Heart of Gold: She's somewhat bratty and kind of shallow but she is overall a sweet natured girl.
- Large Ham: She has tendency to yell out and use all-caps when writing.
- Meaningful Name: Her name means "Diary" in Japanese.
- Mysterious Middle Initial: Her full name is Nikki J. Maxwell. We never find out what the J stands for.
- Oblivious to Love: Simply doesn't get that Brandon clearly likes her back - not even when he kisses her.
- Only Sane Man: Nikki tries to make herself out to be reasonable and she feels other people are idiots. Although she shows Not So Above It All tendencies.
- Surrounded by Idiots: Usually has this mindset when she feels desperate or everyone annoys her.
- Trademark Favorite Food: Nikki really likes to eat Wing-Dings.
- Twice Shy: With Brandon. They've been in love with each other for over eight months and both just don't get that the other likes them back.
Nikki's Love Interest. He appears charming and handsome, but he's also a lovable dorky guy. He works as a school reporter.
- Adorkable: Kind, friendly, a little awkward, and has a good sense of humor.
- Green-Eyed Monster: In Not-So-Secret Crush Catastrophe, when Nikki starts spending time with Andre.
- Heroes Love Dogs: He loves the dogs at Fuzzy Friends and wants them all to find nice, caring homes. When Fuzzy Friends has no room for Holly and her puppies he is genuinely upset at the thought that she might get into a different shelter without a no-kill policy.
- Nice Guy
- Only Sane Man: The most adjusted of the cast.
- Parental Abandonment: He's living with his grandparents. His parents have died.
- Twice Shy: With Nikki. They clearly like each other, but they just can't muster the courage to tell each other. He did finally muster the courage to kiss her in Not-So-Glam TV Star though. Which doesn't mean that they're dating now.
Chloe Christina Garcia
One of Nikki's classmate and Best Friends Forever. Chloe is an avid reader of young adult's romantic novels. She claims to be a dating expert.
- Beta Couple: With Marcus in Not-So-Happy Heartbreaker. It's not clear what became of them after the Sweetheart Dance though.
- Beware the Nice Ones: Usually very nice, but will gladly put the beatdown on anyone who lies or hurts her friends, unless stopped or restrained.
- Bookworm: Owns over 900 books and has read most of them twice. She's also often seen raving about the newest YA novels.
- Divergent Character Evolution: She and Zoey used to be treated as one similar, inseparable pair, but now it's becoming clear that she's the silly one of the duo.
- Motor Mouth: As pointed out when she appears as Goldilocks in Not-So-Happy Ever After.
- Shipper on Deck: She supports the Nikki-Brandon pairing.
- Spicy Latina: She's more temperamental than Zoey and willing to beat up anyone who messes with her friends.
- Straight Man and Wise Guy: Wise Guy to Zoey's Straight Man, especially in later books. Out of the two of them she's clearly the goofier one.
- True Companions: With Nikki and Zoey. They're friends no matter what.
Zoeysha Ebony "Zoey" Franklin
One of Nikki's classmates and Best Friends Forever. She loves reading self-help guides and knows a lot of quotes that she sometimes uses to cheer up her friends, or when she doesn't know what else to say.
- Beta Couple: With Theo in Not-So-Happy Heartbreaker. There's no mention of their budding relationship after that though.
- Cloudcuckoolander's Minder: She tries to keep Chloe in check, who seems to become more goofy with every new book.
- Divergent Character Evolution: In the beginning she and Chloe seemed very similar, but it turns out she's usually the more mature of the duo.
- Shipper on Deck: She would love if her friend Nikki and her love interest Brandon became a couple.
- Straight Man and Wise Guy: Quickly becoming the Straight Man to Chloe's Wise Guy. She's more mature than her friend and keeps an eye on her and her antics.
- True Companions: With Nikki and Chloe. No matter what happens they remain friends.
The most popular girl in Westchester Country Day middle school. Alpha Bitch who leads the CCP (Cute, Cool & Popular) and the main antagonist of the story.
- A Day in the Limelight: Tales from a Not-so-Dorky Drama Queen, after stealing Nikki's diary and writing in it.
- Alpha Bitch: She's the most popular girl at school and she's quite mean to Nikki and others.
- Cheaters Never Prosper: Her attempts at Crippling the Competition are always doomed to fail, and some end up backfiring on her to boot.
- Consummate Liar: She lies all the time to get what she wants or humiliate Nikki. Most people (read: everyone except for Nikki and Brandon, and sometimes the rest of their group) believe her.
- Crippling the Competition: Very fond of doing this - not that it works. Both her attempt to keep Nikki out of the talent show and the time she steals Nikki, Chloe and Zoey's skating costumes don't work as planned. Locking her competition in a storage closet almost did, though...
- Cute, but Cacophonic: Mackenzie certainly is very pretty, but according to Nikki, she has a screechy, nasally voice, as revealed in one of the website's blog posts.
- Drama Queen: Mackenzie is a Drama Queen to the max, and she is proud of it.
- The Fashionista: Throughout the series she is always commented on for her fashionable looks, and she has shown an interest in making fashions as a career.
- Hoist by His Own Petard: Most of her plans to ruin Nikki end up backfiring on her. The one time she does defeat Nikki in the talent show, the latter's band gets a record deal out of it.
- Hypocritical Humor: Mocks her mother for being "totally addicted to lipstick" when she's pretty addicted to lip gloss herself.
- It's All About Me: She's not above lying, manipulating or cheating to get her way. The reason why she messes with Nikki so much is because she sees the latter as a rival.
- Karma Houdini: Let's list some of the things she gets away with shall we?
- She sends Nikki a fake tuition fee, making Nikki think she'll be kicked out of the school if she doesn't pay it. This would get anyone, rich or not, suspended or expelled. No one finds out about this and Nikki doesn't tell anyone.
- Mackenzie not only steals Nikki's identity once, but twice. She gets away with the first one because Nikki's friend guilt trips Nikki into not getting her arrested despite the fact that Mackenzie herself almost got Nikki and her friends arrested. Then she steals Nikki's persona as Miss-Know-It-All when she stole her diary, sending malicious and hurtful replies to the students who sent her the anonymous notes. She gets away with this one because Nikki feared that if she gave the diary to her school they'll read all the escapades Nikki and her friends had in the janitor's closet and spend the rest of their school time in detention since being caught in the janitor's closet is three day's detention.
- Laser-Guided Karma: After transferring schools, she's subjected to the same kind of bullying she put Nikki through.
- Make Way for the Princess: Literally happens in the first book, where Nikki witnesses everyone moving to get out of her way.
- Manipulative Bitch: She manipulates everyone and their mothers to get her way.
- Moment Killer: She has a habit of ruining many a Nikki/Brandon moment and even interrupts two Almost Kiss scenes.
- Narcissist: She knows she is beautiful and is not afraid to let everyone (especially Nikki) know it.
- Not So Different: Aside from the fact that one is rich, snobby and popular while the other is a normal friendly dork, she and Nikki have quite a lot in common (such as their relationships with their younger sisters). Their diary-writing styles are similar too, and both of them started out thinking writing in diaries is lame but ended up getting addicted to it themselves.
- Rich Bitch: Mean and very rich; her father owns a large company and Nikki claims that she spends "twice the gross national product of a small third-world country" on clothes every month. (Nikki was probably exaggerating, but still.)
- Sitcom Arch-Nemesis: Seems to view Nikki as this. She goes out of her way to humiliate her, even before Nikki does anything to deserve that hatred (aka jealousy).
- Unreliable Narrator: In Not-So-Dorky Drama Queen. She tells her version of events that happened in the previous books, and it's very different from Nikki's version of the story. How much she actually believes and how much she's just making up is up for debate, through tying into Not So Different mentioned above, she and Nikki may have been spending a lot of time trying to spite each other from behind-the-scenes.
Nikki's playful younger sister. Usually the source of her older sister's annoyance. She likes playing around with her hand puppet, Ms. Penelope
- Annoying Younger Sibling: Her wacky antics and overactive imagination drive Nikki insane on a regular basis.
- Cloudcuckoolander: She believes unicorns are real, thinks the Tooth Fairy wants to steal all her teeth, and is a neverending source of wacky plans and ideas.
- Genki Girl: Very cheerful and energetic, much to Nikki's dismay.
- Fairy Godmother: Book 8, where her fairy-tale land counterpart plays this to Nikki. She's as ditzy as her real self.
- Foolish Sibling, Responsible Sibling: The Foolish to Nikki's Responsible
- Innocently Insensitive: Has a habit of saying quite rude things to people and being surprised when they get mad. Nikki wonders if she's really this or if she just enjoys messing with her.
- Imaginary Friend: Her talking hand, Ms. Penelope.
- Lethal Chef: When she makes chocolate pudding, she not only adds egg shells to the mixture along with the eggs, she also insists on putting it in the oven instead of the fridge. She does learn to make caramel popcorn balls, however.
- Little Girls Kick Shins: She kicks MacKenzie's shin when mistaking her for the tooth fairy.
- Never My Fault: She blames Miss Penelope for all of her shenanigans, such as stealing snacks or doodling on a poster in her ballet school.
- No Indoor Voice: Like other young children her age, she sure likes to yell a lot.
- Puppy Love: Possibly with Oliver in Not-So-Happy Heartbreaker.
Tiffany Blaine DavenportA phone-obsessed Alpha Bitch who attends the prestigious school North Hampton Hills International Academy. She becomes enemies with Nikki and MacKenzie.
- Phoneaholic Teenager: Tiffany is completely obsessed with selfies and cell phones, and uses them to bully people.