Mary Lou Maloney

Mary Lou Maloney is the main villainess of Prom Night II and Prom Night III: The Last Kiss. She is the ghost of a vindictive girl who was killed in a freak accident on her prom night.

Backstory
Mary Lou was a popular girl in her school and is actively defying authority and sleeping with boys and using them to her own devices. She thinks only for herself and her dream of being Prom Queen. On Prom Night at Hamilton High, 1957, Mary attends with a rich boy named Billy Nordham, who gives her a ring with her initials on it. When he goes to get punch, he catches her making out with another boy named Buddy Cooper. Mary admits to using him and he storms off, before deciding to get revenge by dropping a stink bomb, he acquired from the bathroom on her. When Mary Lou is elected Prom Queen, she walks onto the stage, while Billy drops the bomb from the catwalk. To his and everyone else horror, the bomb ignites in her dress, burning her alive. As Mary Lou dies, she glares at Billy, realizing he's the one who killed her.

Hello Mary Lou: Prom Night 2
In 1987, Vicki Carpenter goes looking for a prom dress at School, and finds a trunk containing Mary Lou's prom accessories, unwittingly unleashing Mary Lou's vengeful spirit. Vicki's best friend Jess Browning arrives, and when she's alone, Jess takes a jewel out of Mary Lou's crown, and is murdered in cold blood by the vengeful spirit. Her death is deemed a suicide, due to her being pregnant. After Jess' death, Vicki has constant nightmares about Mary Lou, and suffers hellish hallucinations. She goes to Buddy Cooper, who is now a local priest. Buddy realizes the presence of Mary Lou's vengeful spirit/ghost, when his Bible burst into flames. Buddy goes to find Billy (Michael Ironside), who is now the principal of Hamilton High, and the father of Vicki's boyfriend, Craig. Buddy's warnings fall to deaf ears, as Billy refuses to believe the story. When Mary makes Vicki hallucinate herself in Vicki's rival, Kelly Hennenlotter, Vicki slaps Kelly. In detention, in another hellish nightmare, Vicki is dragged into a liquid chalkboard and emerges, possessed by Mary Lou. During the possession, Mary Lou visits and mercilessly kills Buddy in cold blood by stabbing him with a miniature crucifix. She later kills and slaughters Vicki's other friend Monica Waters in the locker room without showing any remorse. Mary also seduces Craig and knocks him out. She goes to Billy's house to taunt him and reveal her identity to him. Billy gets a gun after taking his son home, fearing Mary Lou will get revenge on him for killing her back in the past through his son and knocks him out. While Mary Lou is getting ready for prom, she tries to seduce Vicki's father Mr. Carpenter and kills her mother Mrs. Carpenter. The prom, Mary Lou enjoys the festivities, while Kelly, who wants to be queen, preforms an oral sex on Josh, who is running the votes. Mary Lou mercilessly electrocutes Joshua and rigs herself as Prom Queen. Craig arrives trying to stop his father from shooting Vicki, but is too late. He reaches to the apparently dying Vicki who transforms into the charred demonic corpse of Mary Lou herself, which heals back to her living self but still has some burn scars. In the chaos, Kelly is killed by a falling light fixture and Craig is chased into the prop room. A portal to the underworld opens, and tries to suck Craig in, but Billy puts the crown in Mary Lou's head, apparently appeasing her spirit/ghost, thus releasing Vicki. With Mary Lou gone, Vicki and Craig get into Billy's car with Billy. Billy is suddenly wearing Mary Lou's wig before driving off with Craig and Vicki, implying that he is possessed by her ghost.

Prom Night III: The Last Kiss
After the events of Hello Mary Lou: Prom Night 2 Mary Lou was condemned to hell where she was forced to dance in a revealing outfit on a brimstone dance floor. At the opening of the film, she breaks free from her chains with a nail file. After escaping back to earth, Mary encounters a janitor who she recognizes as one of her old boyfriends, and kills him by exploding his peacemaker without showing any remorse.

It turns out after Mary Lou's murderous rampage at the end of the second film, the Hamilton High School went around to rebuild their gym to get ready for a new prom. At the opening of the new gym, the new principal Weatherball, accidental cuts off his fingers, and Mary tries to show her presence by blowing wind through the gym. At the school, a teenager named Alexander "Alex" Gray is aspiring to be a medical student, but is behind on his grades. One night, Alexander leaves a date with his girlfriend named Sarah to collect his text book at the school. There he encounters Mary who seduces him on the American flag.

Alexander develops an unhealthy affair with Mary Lou who helps him with his grades, and football skills, much to the anger of Alexander's rival named Andrew Douglas. Alexander gets a hint of Mary Lou's true nature when Mary Lou kills his biology teacher for giving Alexander a bad grade and has Alexander bury his dead body. In addition to this, the affair puts a strain on his relationship with Sarah.

However, Alexander's grades skyrocket and he makes honor role, much to the suspicion of his guidance counselor, Ms. Richards, who Mary Lou kills with battery acid. At this point, Alexander tries to draw the line by telling Mary Lou not to kill anybody anymore. Despite this Mary Lou kills Andrew on the football field with a football turned spinning drill. Alexander decides to break it off with Mary Lou, much to her anger.

Alexander tries to move on with his life by asking Sarah to prom only to find out that she's going with nerdy student named Leonard Welsh. Alexander also finds out that Mary Lou is stalking him and goes to his friend named Shane Taylor for help. However, Mary Lou kills Shane in cold blood without showing any remorse and has Alexander find his dead body. To make matters worse, Mary Lou has framed Alexander for Shane's murder and the other killings. Alexander is arrested and on the night of the prom, Mary Lou goes to his cell after mercilessly killing two officers. Mary Lou gives Alexander an ultimatum; join her or she will kill Sarah. Alexander refuses and escapes to the Prom to rescue Sarah.

At the school, Mary Lou kills Leonard and tries to kill Sarah who flees to the gym. Alexander arrives and publicly confronts Mary Lou, but agrees to go to hell with Mary Lou to be her eternal Prom King. Mary Lou drags Alexander to hell but Sarah follows to rescue him.

Sarah finds herself in hell which resembles a horrific version of Hamilton High, with its own prom going on. Sarah encounters zombified versions of Leonard, Shane and Andrew, but she fights them off with a makeshift flamethrower, but Mary Lou attacks her with a jukebox that fires buzz saw blades, which cuts one of the lines. At the "prom" Mary Lou is about to kill Alexander but is confronted by Sarah, who uses what's left of the flamethrower to make a makeshift dynamite, and threatens to detonate the prom. They manage to briefly incapacitate Mary Lou before escaping into a garage and sealing a car just as the zombies begin to overwhelm them. As the car starts, Mary Lou tries to stop them only to get run over.

Alexander and Sarah apparently escape back to earth and they stop at a restaurant to use a payphone. There, Mary Lou appears and kills Sarah in cold blood by ripping out her heart and Alexander goes insane admitting that Mary Lou has won.

Trivia

 * She shares the same abilities as Carrie White.
 * Like Mystique\Raven Darkholme, Shang Tsung, Gemini, and Madame Rouge/Laura De Mille, she takes form of any humans by mimicking their voices.