Alfred Leonard Cline (March 12, 1888 – August 5, 1948), known as The Buttermilk Bluebeard, was an alleged American serial killer responsible for murdering at least nine people.

Algimantas Mykolas Dailidė (12 March 1921 – 2015) was a Lithuanian Nazi collaborator who was an official of the Nazi-sponsored Lithuanian Security Police (Saugumas) during World War II. After the war, Dailidė sought refuge in the United States, saying he had been a "forester".

Robert Tyrone Hayes (born March 12, 1982) is an American serial killer who was convicted of three murders in the Daytona Beach, Florida, area between December 2005 and February 2006. DNA tests have also linked him to a fourth murder committed in March 2016.

Mikhail Olegovich Makarov (Russian: Михаи́л Оле́гович Мака́ров; 12 March 1962 – 1988), known as The Executioner (Russian: Палач), was a Soviet serial killer, who from February to May 1986 committed three murders and one attempted murder in Leningrad. He was sentenced to death and executed in 1988.

Christine Laverne Falling (née Slaughter; born March 12, 1963) is an American serial killer.

Ratko Mladić (Serbian Cyrillic: Ратко Младић, pronounced [râtko mlǎːdit͡ɕ]; born 12 March 1942) is a Serbian former military officer who led the Army of Republika Srpska (VRS) during the Yugoslav Wars. In 2017, he was found guilty of committing war crimes, crimes against humanity, and genocide by the International Criminal Tribunal for the former Yugoslavia (ICTY).

Marie Delphine Macarty or MacCarthy (March 19, 1787 – December 7, 1849), more commonly known as Madame Blanque or, after her third marriage, as Madame LaLaurie, was a New Orleans socialite and serial killer who tortured and murdered enslaved people in her household.