When his wife, Marianne, invited the Girls and the Professor over for dinner, Harold took the opportunity to try to destroy them and took Professor as a hostage during the whole dinner, but all he really did was cause a ruckus and ruin the meal. Upon his release from jail in the episode "Just Desserts," Harold's family -- including daughter Julie and son Bud -- joined him as a team of equally inept super-villains (albeit with better costumes), as Marianne's payback for their ruined dinner. They drove a nasty-looking black van with flames painted on the sides of the body, all-terrain, slash-proof, whitewall tires with knives mounted on the hubcaps, blinding three-thousand-watt headlights, spiked bumper, five turbojet engines for optimum speed, six liquid-titanium rocket launchers, rotating laser cannon turret and a spacious leather interior that comfortably seats a family of four to five. The girls eventually destroys their vehicle with a single punch as they demand know why they are doing this?. Marianne finally explains to them about her vengeance is to destroy the Powerpuff Girls for ruining her dinner. The girls realizes that her vengeance is nothing more than a useless reason. As a result, the girls angrily beats them down for the count and they were sent to jail for ruining their home. When the Smiths' house becomes vacant, the Snyder (Schneider?) family (which includes a girl named Robin) from "Superfriends" moves into that house.
Harold is voiced by Jeff Bennett, Marianne and Julie are both voiced by Kath Soucie, and Bud is voiced by Christine Cavanaugh.
- Main article: Harold Smith
An average suburban factory worker, whose ineffectual and timid exterior hides a secret passion for evil. He had an adapted hair-dryer that could melt a person's head, though he never actually had an opportunity to use it. He is a bald man, with a long, banana-like nose and a timid, quivering voice. He wears a pair of square eyeglasses, a pair of stocking, a pair of red thermal underwear, yellow rubber gloves, a holster strapped to one hip, a blue bath mat tied around the neck for a cape, black-rimmed goggles, replacing his square glasses, a hood on top of sparkler. He was arrested by the police for his evil acts that causes his wife, Marianne to revenge the girls for ruining her dinner. In Just Desserts, he was the one behind the wheel to pursue the girls while carrying Professor Utonium in their house but to wreck everything beneath their home. But after his wife reveals her revenge to the girls which it was a useless reason. He and his family are being beaten by the girls angrily and was jailed once again and this time is with his family.
- Main article: Marianne Smith
Harold's very darkly tanned wife, with very light blond hair. She is very weasel-like in appearance, as she has a sharply pointed nose, features bunched up in the middle of her face (as if they're about to sink in), whose excessive perkiness barely disguises a vicious, shrewish side. She wears a black bodysuit and thigh-high boots, with a black mask and blue gloves as well. She was the one who initiated her revenge in Just Desserts as the girls easily realize that her revenge about her dinner was just a useless reason just to wreck their house which resulted herself and her family are been beaten by the girls and are soon jailed for ruining their house.
- Main article: Julie Smith
A simple-minded pudgy little girl with a long blond ponytail and features that almost look drawn on whose life revolves around playing jacks. She wears a black ballet tutu with spikes around its edge, a matching mask and toe shoes. Initially she didn't hate the Powerpuff Girls, but joined her family in their revenge after the Girls lost her jacks. She and Bud are not fighting like their parents but she and her family are now jailed after they ruining the Girls' house and her mother's revenge turns out to be a useless reason which results them being beaten the Girls.
- Main article: Bud Smith
A sullen, green-haired, angst-driven tween with his mother's teeth with braces who hates everything, especially his boring dad. He wears a black outfit with blue gloves and a green cape to match his hair. He and Julie does not fight like their parents even he shows his throwing skills after revealing his villain costume. He and his family are now jailed after they ruining the Girls' house and his mother's revenge for her dinner is nothingmore than a useless reason which results them being beaten by the girls.
- They do not appear in the anime "Powerpuff Girls Z" nor the 2016 reboot.
- They appear in a flashback in episodes "The Boys Are Back in Town" and Night Mayor".
- The voice cast for the Smiths is very similar to that for Dexter's family from Dexter's Laboratory, which was created by Genndy Tartakovsky, and Craig McCracken worked on Dexter's Laboratory as a storyboard artist prior to creating the Powerpuff Girls, where Genndy worked on as an animation director. Jeff Bennett voices both Harold and Dexter's Dad, Kath Soucie voices Marianne and Dexter's Mom, and finally, Christine Cavanaugh voices Bud and Dexter.