The Manson Girls.
You asked for one, but I will grant you three wishes. Just call me Genie.
All of these women (Leslie Van Houten/Patricia Krenwinkel/Susan Atkins) were in their late teens to early twenties in the summer of 1969 when they decided to throw their lives away by doing drugs, having orgies on a Ranch, and murdering people at the behest of Charles Manson. Most of us of a certain age have heard of the Tate/Sebring and the LaBianca murders that took place days apart from each other.
How powerful a grip did the diminutive race-baiter Charles Manson have on these three women that they would kill a house full of people, including a pregnant movie star in Sharon Tate, bathing the walls and house with blood, as well as a grocer and his wife while they rested peacefully in their home?
All of the women involved have been in prison since 1970, Atkins died incarcerated in 2009 from cancer. At the time of her death she was the longest serving female inmate in the Correctional Department of the state of California. Her fellow cohort, Krenwinkel, is now the longest serving female inmate. Leslie Van Houten has been up for parole 23 different times, and is 73 years old as of today. She has long since denounced Manson.
But what a waste of lives for all three of these women. Following that nihilistic madman was the worst mistake any one person or group of people could have made.