Henry Chaplin, 1st Viscount Chaplin PC (22 December 1840 – 29 May 1923) was a British landowner, racehorse owner and Conservative Party politician who sat in the House of Commons from 1868 until 1916 when he was raised to the peerage.

The member of an old Lincolnshire family, Chaplin was born at Ryhall, Rutland, the second son of the Reverend Henry Chaplin, of Blankney, Lincolnshire, and his wife Carolina Horatia Ellice, daughter of William Ellice. His younger brother, Edward Chaplin, was also a politician. Chaplin was educated at Harrow and Christ Church, Oxford, where he was a friend of the Prince of Wales. At the age of 21, he inherited substantial estates in Lincolnshire (including the family seat of Blankney Hall), Nottinghamshire and Yorkshire. He was a Justice of the Peace and a Deputy Lieutenant of Lincolnshire, and a leading member of the Turf.

In 1864, Chaplin fell in love with and became engaged to Lady Florence, daughter of Henry Paget, 2nd Marquess of Anglesey and a celebrated beauty. The wedding was to be the society event of the year with the Prince of Wales one of many to offer his congratulations. However, during their engagement Florence had secretly fallen in love with his best friend, Henry Rawdon-Hastings, 4th Marquess of Hastings. Just before her wedding, she had Chaplin take her to Marshall & Snelgrove's on Oxford Street to add to her wedding outfit. While Chaplin waited in the carriage outside, Florence walked straight through the shop and out to the other side, where Hastings waited for her in a carriage. Hastings and Florence were married on the same day. After the wedding, a reception was held in St James' Place before the newly married couple set off for their honeymoon at Donington Hall, Leicestershire while the scandal died down. Florence Paget informed Chaplin by letter the next day.

In the 1867 Derby, Chaplin renewed his rivalry with Lord Hastings. Hastings wagered thousands of pounds against Chaplin's horse, Hermit. Ten days before the race Hermit was injured and Chaplin was advised not to enter him. However, the injury was not as serious as first thought, and though not fully fit, Hermit entered the race and won it. Lord Hastings lost heavily and fell into severe debts. Adding to a drinking problem, Chaplin's great rival died in poverty the following year, aged 26.

Chaplin first entered parliament at the 1868 general election as Member of Parliament (MP) for Mid-Lincolnshire. He represented this constituency until it was replaced under the Redistribution of Seats Act 1885. In the 1885 general election he was returned to parliament for the new Sleaford division which he held until his defeat at the 1906 general election.

He was a devoted follower and admirer of Benjamin Disraeli, and they struck up a close friendship. Despite their political differences, Chaplin also retained the friendship and respect of the Liberal prime minister, William Ewart Gladstone, until the end of his life. On 29 April 1869 Chaplin delivered his maiden speech on the Irish Church Bill, which disestablished the Church of Ireland.

During the summer of 1875, Chaplin remained in London rather than attend Brighton races, in order to assist Disraeli in supporting the Merchant Shipping Bill against the opposition of Samuel Plimsoll. Disraeli wrote to Lady Bradford on 30 July: "He has never left my side, and his aid has been invaluable. He is a natural orator and a debater too. He is the best speaker in the House of Commons or will be. Mark my words". Chaplin also supported Disraeli's government against Liberal opposition during the debates on the Royal Titles Bill, which conferred on Queen Victoria the title "Empress of India".

Chaplin was a lifelong advocate of protectionism, being in this respect the most prominent inheritor of the views of Lord George Bentinck; his daughter Edith said he was "born a Protectionist, and to the end he remained convinced that Tariff Reform was the only measure which could restore a satisfactory means of livelihood to the English farmer". He was a member of the Royal Commission on the Depressed Condition of the Agricultural Interests (1879–1882) and opposed the Radicals' campaign to replace landlords with peasant proprietorship. The Royal Commission's final report blamed the agricultural depression on excessive foreign competition and the adoption of the gold standard, which had contributed to the decline in prices. Chaplin thereafter became an advocate of bimetallism.