Holly Virginia Jones is the older sister of the protagonist Joey Jones and a key supporting character in the second part of the story. She is an American teenager from Center City on the West Coast who ran away from home four years prior to the main events, driven by her ambition to become a singer. She eventually returns to her family upon hearing news of an alien invasion, though she arrives three months after the initial crisis.

At nineteen years old, Holly has a striking personality that is described as energetic, selfish, and somewhat overbearing. She has a punk-inspired style and a strong-willed, independent nature that often manifests as a nuisance to those around her. Holly operates entirely at her own pace, which frequently results in her dragging her younger brother and his friends into her schemes, making her someone Joey truly fears. Despite her difficult demeanor, she possesses a genuine heart that cares for her family, and she has good singing talent, favoring a ballad style rather than the punk rock her appearance might suggest.

Holly's primary motivation is her passion for music and her career as a singer, which originally led her to leave home. However, her return to Center City is driven by concern for her family's safety during the extraterrestrial threat. Her role in the story evolves from a temporary visitor crashing at her family's home to becoming a new focal point of support for Joey and the giant robot Heroman. She becomes a fan of Heroman after witnessing his heroic actions, and she develops a special interest in the robotic hero.

The most significant relationship in Holly's life is with her younger brother, Joey, whom she tends to boss around and torment upon her return. Her family also includes her grandmother Virginia Jones, father Brian Carter Jones, mother Catherine May-Jones, and her younger brother Joey. She seems to have a particular admiration for Heroman, and she forms a working relationship with other allies such as Matthew Denton and his party. Unlike Joey, who takes an optimistic view of their deceased father, Holly holds a very negative and pessimistic perspective on him, having not properly processed his sudden death. This contrast in viewpoints highlights her unresolved trauma and represents the polar opposite of her brother's heroic idealism. She is selfish in processing this grief, often brushing off Joey's attempts to communicate about their parents.

Holly does not possess any supernatural abilities, but she is a capable singer with considerable talent. Her notable abilities are limited to her musical skills and her forceful, commanding personality that allows her to take charge of situations and the people around her.