Born October 25, 1879, in Hanover, Germany, Haarmann was the sixth child of a real-life odd couple. His father, a surly railroad fireman, was dubbed "Sulky Olle" by acquaintances; his mother, seven years her husband's senior, was an invalid. [ReadOn]

The first woman to die in Ohio's electric chair , Anna Hahn was a German native, born in 1906, who immigrated to Cincinnati at age 21. There, she married a young telephone operator, briefly managing a bakery in Cincinnati's German district before she tired of the hours and set her sights on easy money. [ReadOn]

Newspaper editors licked their lips when details of the crimes of John George Haigh first broke in March 1949. The case had everything:
Here was a young man with the look of a matinee idol claiming to be a vampire and being accused of murdering six people and dissolving their bodies in acid. [ReadOn]

The Haley brothers made a lethal team. Born in 1960 and 1964, respectively, Reginald and Kevin did everything together, sharing drugs and women, ultimately joining forces in a two-man crime wave that would terrorize Los Angeles. [ReadOn]

Drafted by the navy in 1943, despite his best efforts to escape military service , Hall was dishonorably discharged after eight weeks of training. Back home in Little Rock, he married 19-year-old Fayrene Clemmons on March 14, 1944, but their relationship was a stormy one, marked by a brief separation in June. [ReadOn]

Born at Pocahontas, Idaho, in 1940, Hansen was the son of a Danish immigrant who followed in his father's footsteps as a baker. In his youth, Hansen was skinny and painfully shy, afflicted with a stammer and a severe case of acne that left him permanently scarred. (In later years, he would recall his face as "one big pimple.") Shunned by the attractive girls in school, he grew up hating them and nursing fantasies of cruel revenge. [ReadOn]

A homosexual and self-styled occultist , Don Harvey attached himself to the medical profession at age eighteen, working as an orderly at Marymount Hospital, in London, Kentucky, from May 1970 through March 1971. In 1987, Harvey would confess to killing off at least a dozen patients in his ten months on the job, smothering two with pillows and hooking ten others up to near-empty oxygen tanks, all in an effort to "ease their suffering." [ReadOn]

A native of Anniston, Alabama, Hilley was born in 1933 and seemed to enjoy a normal childhood. Married at 18, she was having marital problems nine years later when her second daughter -- Carol -- was born. Psychiatrists, applying hindsight, feel the birth may have somehow triggered a radical shift in Hilley's personality, resentment of the new child simmering over time, finally surfacing in a series of lethal attacks upon family members. [ReadOn]

Baby killer Waneta Hoyt, 52, died on August 13, 1998, of pancreatic cancer at Bedford Hills Correctional Facility in New York state, where she was serving a sentence of 75 years to life for smothering her five children from 1965 to 1971. [ReadOn]