Donald Neilson (1 August 1936 – 18 December 2011), born Donald Nappey and also known as the "Black Panther", was a British multiple murderer and armed robber. Following three murders committed during robberies of sub-post offices from 1971 to 1974, his last victim was Lesley Whittle, an heiress from Highley, Shropshire, England, in early 1975. He was arrested later that year and sentenced to life imprisonment in 1976, remaining in prison until his death 35 years later.

Neilson, known previously as Donald Nappey, married 20-year-old Irene Tate in April 1955 at the age of 18. Their daughter, Kathryn, was born in 1960. After his daughter's birth, Nappey changed the family name to Neilson so that the little girl would not suffer the bullying and abuse he had endured at school and in the army because of his surname's similarity to the word nappy. He was also bullied because of his short stature, five feet six inches. According to David Bell and Harry Hawkes, Nappey bought a taxi business from a man named Neilson and decided to use that name instead of the former. An alternative theory, proposed by a lodger, Miss Lena Fearnley, who stayed with the Neilson family in the early 1960s, is that Neilson took the name from an ice-cream van from which he and Irene often bought ice-cream for their daughter. Miss Fearnley told the BBC in an interview that he told her, "I like that name."