Dylan Piper is the middle child and only son of Gwen and William Piper, grandson of Aggie, younger brother of Marnie, and older brother of Sophie. Dylan is the classic dweeby little brother who agrees with everything his mother says and constantly tries to be the perfect child. He enjoys studying, disapproves of Halloween and all it stands for (to impress his mother), and takes pride in the fact that he is the only "normal" one in the family. He often sarcastically teases his older sister Marnie, whose mindset is the polar opposite of his own. Even though he does turn out to be a warlock, he doesn't like to use magic and prefers to appear normal, like his mother. If his family is in serious trouble, however, he will use his powers to help.
12-year-old Dylan is perfectly content to remain inside during Halloween night to keep his mother, Gwen, happy. He knows that his mother is adverse to the whole concept and as he is something of a momma's boy, he obeys her rules to the letter. This is a complete contrast from his older sister, Marnie, who doesn't understand why her mother never allows them outside on Halloween night and argues in vain that she should be allowed to go out with her friends to a costume party. Dylan even lectures his sister on the dangers of Halloween, asks why she can't like a more normal holiday, like Arbor Day, and states his satisfaction at remaining home, much to her irritation. Soon after their mother has more or less restored order, their grandmother arrives bearing gifts of Halloween costumes, decorations, and candy. Noticing his mother's disapproval, Dylan tries, but not quite manages, to hide his excitement. He cheerfully puts on his troll costume, even though he thinks he looks like a pimple. When his grandma Aggie praises Marnie by saying she must do well in school, Dylan is quick to point out that she only gets B's and C's, and that it is he who earns the A's.
During dinner, his little sister Sophie asks their grandma Aggie to read them all a bedtime story. Though Dylan initially enthusiastically agrees along with Marnie, he sees that his mother is reluctant to allow it and instantly says that it's "a terrible idea". However, Gwen gives in to the request and Dylan is soon wandering over to his sisters' bedroom on the pretense of making sure that their thermostat is set to exactly sixty-eight degrees. Marnie, knowing that he wants to hear the bedtime story as much as she does, tells him to just sit down alreadly, which he gratefully does. Aggie shows her grandchildren a storybook of a magical place called Halloweentown, filled with pictures of ghosts, werewolves, goblins, and a witch that bears a strong resemblance to Marnie. After asking his grandmother to make clear that the place isn't real for the benefit of impressionable young children in the room (meaning Sophie), Dylan declares that the witch in the book doesn't look like Marnie at all; she's too cute. Before Aggie can say much more, Gwen interrupts, saying that their grandmother will have to leave soon if she is to catch her bus home. Before she leaves, however, Gwen asks to have a word with her. As they put away leftovers in the kitchen, Aggie complains that this is Marnie's thirteenth Halloween, an important date that should signal the end of a witch's training. Instead, the half-human Marnie is at risk for losing her powers permanently because her training hasn't begun. Gwen argues that Halloweentown is not her nor her children's world; they belong in the human one. Marnie, who has snuck downstairs, is happily shocked when she witnesses her grandmother turn the chicken leftovers into a live chicken in order to make a point to Gwen. Marnie immediately wakes up Dylan and tells him what she has seen, but he merely thinks she's crazy and hopes that boys are immune. Spotting her grandmother outside walking towards the bus stop, Marnie is excited to see that her handbag is following her like a dog. Dylan is convinced its a kind of animatronic, but Marnie runs to her room and hastily gets dressed while asking her brother if he ever wondered why weird things happen to their family. Dylan says no he hasn't, although his tone of voice indicates that he has. Marnie sneaks outside to follow Aggie and Dylan comes along with her against his better judgement.
The two siblings manage to sneak onto the bus just before it takes off, looking in awe at the creatures around them, although Dylan tries to believe they're merely costume party-goers. When the bus lands, they find themselves in Halloweentown, the fantastic place their grandmother told them about. True to his love for logic, Dylan attempts to explain away the strange things they see by saying it must all be a dream or hallucination. In addition to encountering crazy creatures, they also encounter their little sister Sophie, who had snuck on to the bus even more stealthily than they had. Noticing that they lost their grandmother in their amazement, the trio is relieved when the mayor walks up to them. As he charms Sophie by pulling a giant lollipop out of his ear, they tell him that they are Aggie Cromwell's grandchildren and ask if he knows where she lives. Delighted to hear that their mother is Gwen, an old childhood friend of his, Mayor Kalabar calls them a taxi to take them to Aggie's home. Though driven by a skeleton named Benny, Dylan says that it must be an animatronic like the ones used in Disneyland. When they arrive, Aggie is very surprised but overjoyed that they found their way into her world. Marnie is eager to begin her training, but Aggie is preoccupied with they mysterious behavior of her neighbors; one day they are as nice as they ever were, but the next they are wild and hostile, disappearing altogether soon after. Aggie believes that if she can reignite an ancient family heirloom, Merlin's Talisman, she can fight "the bad thing", as Sophie calls it. The potion that can empower the Talisman calls for the hair of a werewolf, a vampire's fang, and the sweat of a ghost, ingredients that shouldn't be too hard to find in town. As the shopping trip will also allow her to show them her world, she happily takes along her grandkids.
Marnie is delighted by the discovery of broomsticks and begs her grandmother to buy one for her, who not only complies but also takes Marnie on a ride. But before Aggie can take Sophie on a flight, Gwen appears, furious at her mother for taking away her children without her knowledge. Dylan instantly tries to explain that he told them not to go and that he said it was a bad idea from the start. Gwen orders her children to say goodbye and then to come home with her. As Gwen tries to find out the departure time of the next bus, Marnie rants about how unfair her mother is. Finding out that the bus has been delayed, Marnie smugly declares that they'll just have to stay. Ever-helpful Dylan suggests asking the mayor for help, and idea to which Gwen agrees. Mayor Kalabar, overjoyed at seeing Gwen again, flirts with her, making Dylan reel with tweenage disgust. Catching sight of her grandmother walking somewhere with the town punk, Luke, Marnie senses her grandmother is in trouble runs after her in case she needs help, causing her mother and siblings to chase after her.
Luke takes Aggie to the abandoned movie theatre, where she discovers all of the people who have disappeared frozen like statues. Noticing a dark, swirling vortex where the movie screen should be, she soon comes face-to-face with the mastermind behind the disappearances, a creature swathed in shadow. He commands that she give him the Talisman, but she naturally refuses, instead demanding to know why he has kidnapped all these people. At that moment, her family bursts in. Marnie starts forward to help, but her mother orders her to keep her younger siblings back, rushing to help Aggie herself. As the shadow being throws magical fire at Aggie, Gwen shoves her out of the way, getting hit herself in the process. The spell paralyzes Gwen in time, and Aggie, struck with horror, is unable to dodge a second fireball. Struggling against the freezing curse, she tells her grandchildren to escape before she succumbs to the spell. An upset, terrified Marnie wants to stay and do something, but Dylan drags her away so that they may come up with a plan. The siblings decide to rescue their mom and grandmother by gathering the potion ingredients and reigniting Merlin's Talisman.
First on the list is the hair of a werewolf, which they find at a hair salon. Marnie tries to distract the werewolf beautician by first asking about part-time jobs, then by turning on a hair dryer that shoots out flames. While the werewolf is frantically attempting to instruct Marnie how to turn the device off, Dylan creeps up behind him and shaves off some hair from the back of his head. The next ingredient, sweat of a ghost, is harder to find. Can ghosts sweat without bodies? Nevertheless, the siblings check out the recreation center, figuring that sweat of all kinds could be found there. As they explore, they happen to discover a sweat box and a large ghost who is nestled inside. Marnie, after telling Dylan to distract the ghost, wanders over to the temperature control and increases the heat. Dylan awkwardly tries to engage the ghost in trivia, but it is Sophie who succeeds in seizing the ghost's attention by pretending to be a ghost herself. Marnie is able to swipe a drop of sweat off the ghost's nose and the children run off to find the final ingredient, a vampire fang, at the dentist's. Luckily for them, a vampire is getting her tooth pulled. Marnie, disguised as an assistant, takes the fang and hurries to join her siblings, who are waiting outside where they all nearly get run over by Benny's taxi. The skeleton offers to take them back up to Aggie's house free of charge and Dylan gratefully agrees before Sophie pulls him back. She says that the "bad thing" is in Benny. Dylan is confused and perhaps a touch worried, a fear that grows when Benny becomes impatient and orders them to get in the car. Before the children can turn away, Benny lunges at a frightened Dylan and grabs him by the neck, trying to yank him into the taxi. Marnie and Dylan struggle against the surprisingly strong bones while Sophie releases a dog from its leash, telling it to "go fetch the bone", scaring Benny off. Massaging his throat, Dylan thanks his little sister for saving him.
With the potion complete, the Talisman is nearly ready. Unfortunately, Marnie has completely forgotten the spell that activates it, to Dylan's disbelief. After attempting two spells of her own creation that fail to work, Sophie comes to their rescue because she made a song out of the spell's words. Joining forces with her sister, they chant the spell together and cause the Talisman to illuminate at last. Believing that the Talisman can cure their mother and grandmother, the siblings rush to the abandoned theater and wave the Talisman in vain over their family members, becoming distraught when it fails to do anything. Discouraged, Marnie remembers her grandmother telling her that the Halloween traditions in the human world are merely echoes of Halloweentown's traditions. Gazing at the shining Talisman, Marnie tells Dylan that it's similar to the candles that humans place into their Jack-O-Lanterns. Recalling that there is an enormous, empty Jack-O-Lantern in the center of town, Marnie realizes she must install the Talisman within its orange depths.
Dylan keeps Sophie safe and stays out of the way while Marnie attempts to light the darkened pumpkin, rejoicing when Marnie eventually succeeds and they are reunited with their mother and grandmother. Kalabar, however, the shadow being behind the "bad thing", soon overcomes the pain that the Jack-O-Lantern's returned light has caused him and laughingly faces the Cromwells. He magically forces the Talisman to fly into his hand and dares the Cromwells to try their best to stop him. Enraged at Kalabar's taunts, Dylan's fingers begin to spark with magical power. At first he is horrified, professing that because he is the "normal" one in their family he simply can't be a warlock. But seeing that Gwen and Aggie alone aren't strong enough to overpower the twisted mayor, Dylan joins hands with the four Cromwell witches and combines his newly-discovered powers with theirs. Kalabar is no match for five Cromwells and his shroud of shadow ignites, causing him to dissolve into bright, magical light.
As the Cromwell family celebrates with the citizens of Halloweentown, her grandchildren state that they want to stay with Aggie longer, but the bus between worlds only travels once a year on Halloween. Knowing this, Gwen asks Aggie to live with them in the human world. Stunned that her daughter would ever make such an offer, but delighted at the prospect of spending more time with her family and training her grandchildren, Aggie happily agrees. All five Cromwells embark on the bus and wave goodbye to Halloweentown as they take off for the human world.
Halloweentown II: Kalabar's Revenge (2001)
At age 14, he tries to reach out to girls, but only ends up getting ditched and only uses his powers twice to help fix the worlds, first using them with his family and Luke to create a new permanet portal between the worlds and then (reluctantly) with the prodding of Luke to break the spell on Benny.
Halloweentown High (2004)
He doesn't use his powers at all and falls for a girl before finding out she was a pink troll. Though he doesn't use magic at all in this movie, he states that he has tried to apologize to Natalie using magic to speed-up the speaking process.
Return to Halloweentown (2006)
At age 17, he attends Witch University with his sister, and confesses that he used his powers to study rapidly in high school, which is the reason to why he skipped a grade and is able to attend college with his sister, Marnie. He also falls for the evil Sinister sisters but they use him to get the Gift- his family heirloom, so they can try to take over Halloweentown. Later he becomes the wielder of the Gift but decides to hide it in a book.He ends up using magic a few times in this movie: he speed-reads in order to get information on Splendora, admits to using it in high school and uses it to destroy the Gift as it takes three Cromwells to do and only he, Gwen and Marnie were around. This is the most amount of times he uses his powers in the movies. At the end of the movie, he finds the Gift in a box which means his sister didn't destroy it.
Dylan Piper was portrayed by Joey P. Zimmerman in all four films.
Due to his growth spurt after the first film, younger viewers thought someone else was cast in the sequels.
- Gwen Piper is Dylan's mother. Although she can be considered overprotective of her children, Dylan doesn't seem to mind. In fact, he agrees with everything his mother says, eager to be the perfect child. He strives to get straight A's in school, tries to encourage his sisters to obey their mom, and takes her side in nearly every argument. Probably because of this mindset, he doesn't like to use magic if he can help it and prefers to appear human rather than explore his powers.
- William Piper is Dylan's father. He is human, but died sometime before the first movie. Ever since his father's death, Dylan has tried to be the man of the house. Little is known about their relationship, but he seems to respect and love his father very much. It's possible that his love for his father contributes to his desire to appear human.
- Aggie Cromwell is Dylan's grandmother. Although he is excited by Aggie's visits and clearly loves her a lot, he knows that his mother disapproves of her visits and therefor tries to disapprove of them too. He argues with Marnie that it's his grandmother who starts fights with Gwen, not the other way around. In the first movie, he encourages Aggie to explain to impressionable young Sophie that the Halloweentown in her storybook isn't a real place. Despite this, he is delighted by her visits every bit as much as his sisters are, even if he attempts to hide it.
- Marnie Piper is Dylan's older sister. The two are polar opposites in almost every way and so unsurprisingly, the two bicker with each other often. Although they can seriously annoy one another, they do care about each other deep down. He attends high school and college with Marnie in the later movies.
- Sophie Piper is Dylan's younger sister. It is often Sophie who convinces Dylan to take part in whatever they're experiencing, be it with a look or holding out her hand to him. He seems protective of his little sister and is concerned about being a good role model for her.
- Natalie is Dylan's love interest in the third movie. Dylan develops a crush on the pretty, fun Natalie, and it appears that she returns is affections. Although he knows fully well that she comes from Halloweentown, he is nevertheless unpleasantly surprised, almost disappointed, when he discovers that she's naturally a bright pink, hairy troll. His reaction to her true self is offensive and she becomes upset with him, telling him that in her world she is considered beautiful and that he, with his pale, hairless skin, is one of the ugliest creatures she has ever seen. But she doesn't care about his outward appearance, it is what is on the inside that counts. She had hoped that he would think the same way, and is sad that he doesn't seem to.
- "I can't believe mom dated that guy." - Dylan after Kalabar shedded his shadow hooded demon disguise
- "Are you crazy?! That shadow thing is gonna turn us gonna turn us into statues!" (Marnie: "It isn't gonna follow us. Didn't you see? It can't stand the light.") - Dylan after he, Marnie and Sophie ran out of the abandoned movie theater to save themselves from getting frozen in time by Kalabar, who's disguised as a shadow demon
- "He got her and it's not working! We've lost! We've... (Sophie hits him) Ow!" - Dylan after seeing Kalabar nearly freezing Marnie in time when she tried to install Merlin's talisman into the Jack-O-Lantern at the center of Halloweentown so she can save it and the mortal world, complaining about it until Sophie hits him to stop
- Dylan's birth year has seemingly changed throughout the films. In Halloweentown, Dylan is about 12, which makes his birth year 1986. In Halloweentown II: Kalabar's Revenge, Dylan is 14, which makes his birth year 1987. In the last two films, his birth year is apparently 1989.
- His grandmother gifted him a troll costume in the first movie. He thought he looked like a pimple.
- He is the only Cromwell child who prefers being human rather than magical.
- When Marnie first mentions their late father in the first movie, Dylan tells her to be quiet because mentioning their dad upsets their mom.
- He is similar to Nick Szalinski from another Disney series, Honey I Shrunk the Kids as both kids are nerds and have hit a huge age difference and have love interests by the time the first sequel is released.