Aileen Carol "Lee" Wuornos was an American serial killer and sex worker who murdered seven men in Florida in 1989 and 1990 by shooting them at point-blank range. Wuornos claimed that her victims had either raped or attempted to rape her while they were soliciting sex from her, and that all of the homicides were committed in self-defense. She was sentenced to death for six of the murders and was executed by lethal injection on October 9, 2002.

The Freeway Phantom is a media epithet for an unidentified serial killer who was active in Washington, D.C. from April 1971 through September 1972. They murdered six people.

Herman Webster Mudgett was an American serial killer active from December 1891 to November 1894. Despite his confession of 27 murders, Holmes was convicted and sentenced to death for only one murder. His victims were killed in a mixed-use building which he owned in Chicago, supposedly called the World's Fair Hotel (informally called "The Murder Castle"), though evidence suggests the hotel portion was never truly open for business. Besides being a serial killer, Holmes was also a con artist and a trigamist, the subject of more than 50 lawsuits in Chicago alone. Holmes was executed on May 7, 1896, nine days before his 35th birthday.

Rodney James Alcala is an American serial killer and rapist who was sentenced to death for five murders committed in the state of California between 1977 and 1979. He received a further sentence of 25 years to life after pleading guilty to two homicides committed in New York in 1971 and 1977. Alcala's true victim count remains unknown, and could be much higher. He is sometimes referred to as The Dating Game Killer because of his 1978 appearance on the television show The Dating Game in the midst of his murder spree.

Ricardo Leyva Muñoz Ramírez, also known as Richard Ramirez, was an American serial killer, serial rapist, kidnapper, pedophile, and burglar. His highly publicized home invasions and murder crime spree terrorized the residents of the Greater Los Angeles area, and later the residents of the San Francisco Bay Area, from June 1984 until August 1985. He used a wide variety of weapons, including handguns, knives, a machete, a tire iron, and a hammer. He also made use of Satanic imagery. In 1989, Ramirez was convicted of thirteen counts of murder, five attempted murders, eleven sexual assaults, and fourteen burglaries. Ramirez was sentenced to death. He died of complications from B-cell lymphoma while awaiting execution.

The Zodiac Killer is the pseudonym of an American serial killer who operated in northern California from at least the late 1960s to the early 1970s. The unidentified killer would send a series of taunting letters and cards to the San Francisco Bay Area press. These letters included four now infamous ciphers. The Zodiac murdered five known victims between December 1968 and October 1969. He targeted young couples. He also murdered a male cab driver. The Zodiac himself once claimed to have murdered 37 victims, and he has been linked to several other cold cases.

Henry Lee Lucas was an American serial killer whose crimes spanned from 1960 to 1983. He was convicted of murdering 11 people and was sentenced to death for the murder of Debra Jackson, though his sentence was later commuted to life imprisonment in 1998. Lucas rose to fame after confessing to more than 100 murders while in prison. He died of congestive heart failure in 2001.

Jeffrey Lionel Dahmer, known as the Milwaukee Cannibal, was an American serial killer who murdered and dismembered 17 men and boys between 1978 and 1991. Dahmer sought out men, mostly African American, at gay bars, malls and bus stops, lured them home with promises of money or sex, and gave them alcohol laced with drugs before strangling them to death. He would then engage in sex acts with the corpses before dismembering them and disposing of them, often keeping their skulls or genitals as souvenirs. Dahmer was convicted of 16 murders and was sentenced to 16 terms of life imprisonment on February 15, 1992. On November 28, 1994, Dahmer was beaten to death by Christopher Scarver, a fellow inmate, at the Columbia Correctional Institution in Wisconsin.

Daniel LaPlante is an American murderer who was convicted of killing Priscilla Gustafson and her two children back in 1987 when he was only seventeen years old. LaPlante was a very troubled kid, having a history of breaking into people's homes and taking their possessions. He even broke into the house of an ex-love interest, lived in her walls for two months, and tormented her and her little sister with tapping sounds and mysterious writing on their walls. He is currently serving multiple life sentences for his crimes.

In this episode, Grace and Olivia discuss the crimes committed by one of the Soviet Union's worst serial killers, Andrei Chikatilo. Known by some as the "Butcher of Rostov," Chikatilo sexually assaulted, murdered, and mutilated at least fifty-two women and children between 1978 and 1990. Even though he was formally convicted of fifty-two murders, Chikatilo has claimed to have taken the lives of over fifty-six.