Donald Neilson (also known as the "Black Panther") is a British serial killer, whose most notable victim was Lesley Whittle from Highley, Shropshire, England.

A jobbing builder in Bradford, West Yorkshire, Neilson turned to crime when his business failed. It is believed he committed over 400 house burglaries without detection during his early days of crime. Proceeds were low, however, which resulted in him turning to robbing small post offices.

His crimes became more and more violent and already having fatally shot three sub-postmasters in post office robberies, the Whittle case made him Britain's most wanted man in the mid-1970s.

Lesley Whittle was a 17-year-old girl and was Neilson's youngest and best-known victim.

On 14 January 1975, Whittle was kidnapped from the bedroom of her home in Shropshire, England. Neilson demanded a £50,000 ransom from her family for her release. Her mother was asleep in the house at the time. The kidnapper had read that Whittle had been left a considerable sum of money (£82,000—almost half a million pounds compared to 2007 figures) by her late father George (who died in 1967 at the age of 62), who ran a successful coach company, one of the largest in the country, based at Highley and Kidderminster.

A series of police bungles and other circumstances meant that Whittle's brother Ronald was unable to deliver the ransom money to the place and time demanded by the kidnapper, who, it is widely believed, pushed Whittle off the ledge in the drainage shaft where he had tethered her in Bathpool Park, at Kidsgrove, Staffordshire, strangling her. Whittle's body was found on 7 March 1975, hanging from a wire at the bottom of the shaft.

In December 1975, two police officers, Tony White and Stuart Mackenzie, spotted a man acting suspiciously outside a post office in Mansfield Woodhouse, Nottinghamshire. As a matter of routine, they stopped to question him. The man said he was on his way home from work, then produced a sawed-off shotgun from a parcel he was holding. He ordered White back into the car, then sat in the passenger seat with the gun jammed into Mackenzie's ribs.

He ordered them to drive to Blidworth, six miles away. As they were driving along Southwell Road the gunman asked if they had any rope. As White pretended to look, he saw that the gun was no longer pointing at his companion; he pushed the gun up and Mackenzie stamped on the brake. They were outside The Junction Chip Shop in Rainworth and called for help. The gun went off grazing White's hand. Two men ran from the queue outside the fish and chip shop and helped subdue Neilson. The locals attacked him so severely that in the end the police had to protect him.

They handcuffed Neilson to iron railings at the side of a bus stop, and when they found two Panther hoods on him, they realised that they had probably caught the most wanted man in Britain. This was confirmed when his fingerprints were found to match one of those found in the drain shaft with the body of Lesley Whittle.

Neilson was sentenced to life imprisonment in July 1976 for the murder of Whittle, three sub-postmasters and the attempted murders of a security guard and a police officer. The trial judge recommended that Neilson receive a whole life tariff. He has since been confirmed on the Home Office's list of prisoners issued with whole life tariffs, as a succession of Home Secretaries have ruled that life should mean life for Neilson. The European Court of Human Rights legislation saw politicians lose that power in November 2002.

In 2008, Neilson applied to the High Court to have his minimum term reverted to 30 years. On 12 June 2008, however, Neilson's appeal was rejected, and he was told by the court that he will have to spend the rest of his life in prison.

Now in his seventies, Neilson continues to serve his sentence at HMP Full Sutton and remains one of Britain's longest-serving prisoners.