Lisa Morrison is the central character of The Grudge 3. She is a young woman living with her older brother Max and her younger, chronically ill sister Rose in a Chicago apartment building that has become the new home of a supernatural curse known as the grudge, which was brought into the building through a previous resident. Lisa is initially portrayed as pragmatic and somewhat dismissive of the supernatural, focused on her personal plans to move to New York City to pursue a career in fashion. She has a close but strained relationship with Max, who is the building superintendent and who resents having to care for Rose alone after their parents died. Lisa's boyfriend Andy is another key figure in her life, though his presence also creates tension with Max.

Her motivations shift as the curse begins to claim lives around her. When a woman named Naoko arrives from Japan claiming to know how to stop the grudge, Lisa refuses to participate in the exorcism ritual. However, she reconsiders after witnessing Max become possessed by the spirit of Takeo Saeki, realizing that her family is directly threatened. Her role in the story is that of a reluctant protector who must confront the curse to save her siblings. She eventually agrees to help Naoko, but the ritual goes wrong when Naoko is killed before it is completed. In the climactic confrontation, Lisa is chased by Kayako, the ghost at the heart of the curse, but is spared when Rose drinks Kayako's blood in an attempt to transfer the curse into herself. After the ritual, Max is killed by Naoko's vengeful spirit, and Lisa is left with a traumatized Rose. The final moment reveals that the curse has not been truly lifted, as Lisa is seen embracing what appears to be Kayako now inhabiting Rose's body.

Throughout the story, Lisa undergoes significant development from a skeptical, career-minded young woman into someone willing to sacrifice her own safety for her family, though she ultimately cannot fully escape the curse. She demonstrates a practical nature and a protective instinct, yet her initial refusal to believe in the supernatural leaves her unprepared for the dangers she faces. Notable abilities are limited to her determination and resourcefulness; she does not possess any supernatural powers but shows resilience in confronting the ghosts and navigating the ritual. Her key relationships are with her siblings Max and Rose, as well as with Andy, and her interactions with Naoko are critical to her understanding of the curse. Lisa's character serves as the audience's entry point into the final chapter of the American grudge trilogy, embodying the struggle to break a cycle of violence and haunting that seems impossible to stop.