Stacey Ann Lannert (born May 28, 1972, St. Louis, Missouri) is an American woman convicted of the murder of her father, Tom Lannert when she was 18 years old. She testified that he had sexually abused her since she was 8 years old. Sentenced to life in prison without the possibility of parole, she served 18 years.

On January 10, 2009, outgoing Missouri Governor Matt Blunt commuted Lannert's sentence and that of another woman convicted under similar circumstances. He said, "After an exhaustive review of the facts in both cases, I am commuting the sentences of Stacey Lannert and Charity Carey, who suffered extensive abuse before they took action against the men who raped them and subjected them to other horrible physical and emotional abuse." Lannert's new sentence of 20 years made her eligible for immediate conditional release, and she was released on January 16, 2009.

Lannert founded a resource website and non-profit organization, Healing Sisters, to aid women who have suffered abuse. In 2011, she published a memoir about her experiences, Redemption: A Story of Sisterhood, Survival, and Finding Freedom Behind Bars.

Stacey Lannert was born in St. Louis, Missouri in 1972, the daughter of Deb Underwood and Thomas Lannert. She has said that she was close to her father and he made her feel special, but he was drinking to excess and started sexually abusing her when she was eight and raped her at nine. Her parents divorced when she was young. Although she tried to tell her mother and a babysitter about her father's rapes, she did not have the language to make them understand, and he had threatened her to keep her quiet. Her sister Christy, two years younger, has said their father physically abused and beat her from when she was in first grade, becoming especially violent when drinking.

Stacey Lannert went to live with her mother, then in Guam, six months before the murder. Her sister Christy begged her to return, and Lannert tried to persuade her father to let Christy live with her and her mother. He would not let her go.

At the age of 18, in the town of St. John, Missouri, Lannert shot her father twice while he was sleeping on a sofa. Later, after confessing to killing him, she said that he had repeatedly raped and abused her as a child, threatening her so she would maintain secrecy. She said that, based on fears for her sister, she had decided to kill him to stop him.

She testified that on July 4, 1990, she and her sister got home late, entering the house via a basement window at approximately 4:15-4:30 am. Seeing a rifle, she decided to kill her father. Finding her father asleep on the sofa, she shot him. This shot broke his collarbone and startled him awake. In fear, Stacey closed her eyes and shot again. The next day, she consulted with an adult friend, who encouraged her and helped her to dispose of the murder weapon. She called the police, pretending to have found her father dead on the sofa upon returning home.