Penny

Penny is Bolt's former Owner and The Main Antagonist in the climax of Descendants Four. She was the one that realized the villains for her own motive. To Take Over Auradon after years of rejection and heartbreak. However she is NOT the main antagonist and is a good character in BOLT 2 and Bolt 2: Body Switch

Personality
Penny is a kind, lovable, and intelligent 13-year-old girl. Ever since she was little she loved Bolt dearly and was heartbroken when she found out he ran away. She clearly isn't fond of her agent who rarely listens to her and tries to persuade her into doing what he wants. She is also very loving towards all animals, including Mittens and Rhino, whom she presumably found at the hospital and adopted. But in Desendants 4, Penny finally snaps after all those years of harassment and heartbreak that happened to her unaware to Bolt.

Bolt (canon film)
Penny was 8 when she adopted Bolt in the Silverlake Animal Rescue, who lived with the puppies of the shelter and his favourite toy Mr. Carrot. Five years later, she and Bolt became the stars of the hit TV show Bolt, where they foiled the evil plots of the nefarious Dr. Calico. However, Bolt believed everything that he saw to be real, and that he had superpowers, Bolt was assigned the task of protecting Penny from Calico’s henchmen. In one of the episodes, she and Bolt are in a large city, where they are spying on Calico. After interrogating one of his thugs and learning of his location in Bolivia, Penny was pursued on her fold-up scooter by Calico's helicopters and motorcycles. One of the men tried to lead Bolt away by deploying a disc-shaped bomb on the back of a gas tanker, but Bolt swiftly dispatched the bomb and reunited with his person. Then, Bolt used his super bark on the forces that surrounded the airport. Having accomplished their mission, Penny poses for a Polaroid picture with Bolt before carrying him through the debris of "super barked" cars and "unconscious" evil henchmen into their set trailer. Penny adds the newest picture to her wall of countless pictures of her and Bolt before trying to play with Bolt, who is convinced the henchmen will come back for Penny and is determined to protect her. Sadly, Penny hugs Bolt goodbye for the weekend and leaves him in his trailer.

Saddened about having to leave Bolt alone again, Penny pleads to her agent to take Bolt home for the weekend, but the agent simply tells her to "put a pin in it." She is then later taken by the rest of the staff to be on a cover shoot while Bolt gets bullied by one of Calico's feline henchmen. The next day, Penny and her dog Bolt "infiltrate" Calico's secret lair in Bolivia, where they try to get information to where her father is. However, Calico appears and begins to "kidnap" Penny, resulting Bolt being taken back to his trailer after the shooting ends. As a result, Bolt escapes and Penny tries to get him back by sending out lost dog flyers. However, Mindy Parker from the network reminds her that they have to keep in production, or else good people will start losing their jobs.

After undergoing a cross country journey back to Hollywood from New York, Bolt reaches the studio, finding Penny embracing his lookalike. Unaware that Penny still misses him and that her affection for the lookalike was only a part of a rehearsal for the show, he leaves, broken-hearted. Mittens, on a gantry in the studio, sees what Bolt does not - Penny telling her mother how much she misses Bolt. Realizing that Penny truly does love Bolt, Mittens follows Bolt and explains. At the same time, during a shooting of an episode, Penny is being held "captive" by Dr. Calico until the Bolt-lookalike arrives to "rescue" her, along with her father. However, the Bolt-lookalike panics during filming and accidentally knocks over torches, setting the sound stage on fire and trapping Penny. Bolt arrives and reunites with Penny inside the burning studio, being rescued by firefighters as they succumb to smoke asphyxiation.

Penny and her mother subsequently quit the show when their agent attempts to exploit the incident for publicity purposes. The show continues with a new actress replacing her and also with a new alien abduction storyline, while Penny herself adopts Mittens and Rhino, and moves to a rural home to enjoy a simpler, happy lifestyle with Bolt and her new pets. After watching the said episode, Penny takes a selfie with her new pets and begins to play outside with them, enjoying their new life outside Hollywood.

Audrey X Carlos
Although Bolt is a main character in Audrey X Carlos, Penny and the other bolt characters aren't seen or even mentioned. Bolt ends up living with Carlos instead.