Detective Inspector Jonathan Whicher (1 October 1814 – 29 June 1881) was an English police detective. He was one of the original eight members of London's newly formed Detective Branch, which was established at Scotland Yard in 1842. During his career, Whicher earned a reputation among the finest in Europe.

In 1860, he was involved in investigating the Constance Kent murder case, which was the subject of Kate Summerscale's 2008 book The Suspicions of Mr Whicher, as well as the film of the same name. He was one of the inspirations for Charles Dickens’s Inspector Bucket, Colin Dexter’s Inspector Morse, Wilkie Collins's Sergeant Cuff and R. D. Wingfield's Jack Frost, among other fictional detectives.

Whicher was born in 1814 in Camberwell, London, the son of Rebecca and Richard Whicher, a gardener. He was baptised on 23 October 1814 at the church of St Giles in Camberwell. After working as a labourer he passed the physical and literacy tests and joined the Metropolitan Police on 18 September 1837 as a police constable with the number E47 (Holborn Division). Whicher was 5' 8" tall, with brown hair, pale skin and blue eyes. He married Elizabeth Harding (born 1818), and they had a son, Jonathan Whicher (born 1838), who died young. By 1841 he was living in a police dormitory at a stationhouse in Gray's Inn Lane in St Pancras. In August 1842 he and seven other men joined the newly formed Detective Branch at Scotland Yard. Whicher received the new number A27 (Whitehall Division) and was promoted to detective sergeant shortly after. Whicher was reportedly described by a colleague as the "prince of detectives". Charles Dickens, who met him, described him as "shorter and thicker-set" than his fellow officers, marked with smallpox scars and possessed of "a reserved and thoughtful air, as if he were engaged in deep arithmetical calculations". William Henry Wills, Dickens's deputy editor at Household Words magazine, saw Whicher involved in police work in 1850 and described him as a "man of mystery".

In May 1851 Whicher was accused of entrapment when he and Inspector Lund saw John Tyler, a convict who had been transported to Australia as a criminal and had recently returned, in Trafalgar Square. Whicher and Lund watched Tyler meet William Cauty, another known criminal, and sit with him on a bench in The Mall opposite the London and Westminster Bank in St James's Square. Whicher and Lund watched the two as they returned to the same bench every day for six weeks and watched the bank. Eventually, on 28 June 1851 they caught the two red-handed as they ran from the bank having robbed it. The Times criticised the police for allowing the crime to take place rather than preventing it. Whicher also pursued criminals who counterfeited coins, forged signatures on cheques and money orders, as well as pickpockets and conmen.

In 1854 Whicher was involved in the capture of the valet who stole ten pictures including the 'Virgin and Child' by Leonardo da Vinci (then valued at £4,000) from the home of the Earl of Suffolk near Malmesbury. The valet and his accomplices were unable to sell the pictures and they were discovered under one of the arches of Blackfriars Bridge. Whicher was promoted to detective inspector in 1856.

When Italian revolutionaries organised by Felice Orsini tried to assassinate Napoleon III in 1858 in Paris, Whicher took part in the hunt to track them down. In 1859 he investigated when the Reverend James Bonwell, the married rector of St Philip the Apostle in Stepney and his lover Miss Lizzie Yorath, a clergyman's daughter, were charged with murdering their illegitimate son. Bonwell had paid an undertaker 18 shillings to bury the dead child secretly in a coffin with a deceased stranger. The couple were found not guilty of murder but were censured by the jury, and in 1860 Archibald Tait, the Bishop of London, sued Bonwell for misconduct. In early 1860 Whicher caught Emily Lawrence and James Pearce, who had stolen £12,000 worth of jewellery from jewellers' shops in Paris by examining valuable items on trays and then palming them.

Detective Inspector Jack Whicher's fame had spread, and he was at the height of his powers when in July 1860 he was sent by Scotland Yard to assist the local police in the small village of Rode (then in Wiltshire) in investigating the murder of 3-year-old Francis Saville Kent. By this time Whicher had already solved several notorious crimes and had gained a reputation for being able to solve the most difficult cases. Francis Saville Kent had been taken from his nursemaid Elizabeth Gough's bedroom during the night of Friday 29 June 1860 and his body was found the next morning dumped in an outside privy used by the servants in the garden of his family's house. His throat had been cut, among other injuries.

Local Police Superintendent Foley believed that the nursemaid, Elizabeth Gough, who had responsibility for Francis Kent, who slept in her room, was involved in the murder. His theory was that she and a lover, possibly the child's father, had woken the child up and had killed him in order to silence him, at the same time opening a window to make it look as if an intruder had gained access to the house and had killed the child. During the early part of the investigation, a heavily bloodstained nightgown was found lodged in a chimney in the house. Superintendent Foley ordered that this should be replaced so that a watch could be kept on it, hoping that the murderer would return to destroy this crucial piece of evidence. This went wrong when the two constables ordered to watch over the nightgown were locked in the kitchen. Before they were released the nightgown had vanished. Foley was afraid that the incompetence of his officers might result in punishment for him and for them. As a result, he deliberately did not inform the authorities of the find and its subsequent disappearance.