* Herbert Austin ( 1866 – 1941 ), British founder of the Austin Motor Company

* 1866 – The Grand Army of the Republic, an American patriotic organization composed of Union veterans of the American Civil War, is founded.

* 1866 – Felix-Raymond-Marie Rouleau, Canadian cardinal of the Roman Catholic Church ( d. 1931 )

* 1866 – Princess Viktoria of Prussia ( d. 1929 )

* 1866 – Allen Lard, American golfer ( death date unknown )

* 1866 – Giovanni Agnelli, Italian businessman, founded Fiat S. p. A ( d. 1945 )

* 1866 – Gábor Klauzál, Hungarian politician ( b. 1804 )

* 1866 – Matthew Henson, American explorer ( d. 1955 )

* 1866 – José de Diego, Puerto Rican statesman and journalist ( d. 1918 )

* 1866 – Charles Jean de la Vallée-Poussin, Belgian mathematician ( d. 1962 )

* 1866 – Italo Santelli, Italian fencer ( d. 1945 )

* 1866 – Jacinto Benavente, Spanish writer, Nobel Prize laureate ( d. 1954 )

* 1866 – Henrik Sillem, Dutch sports shooter ( d. 1907 )

* Alexander John Cuza, prince of Romania ( 1859 – 1866 )

* 1866 – Austro-Prussian War ends with the Treaty of Prague.

* 1866 – Anne Sullivan, American teacher, instructor and companion of Helen Keller ( d. 1936 )

* 1866 – Ernest Starling, British physiologist ( d. 1927 )

* 1866 – Italy and Prussia ally against the Austrian Empire.

* 1866 – The American Society for the Prevention of Cruelty to Animals ( ASPCA ) is founded in New York City by Henry Bergh.

He married fourthly at the Dolmabahçe Palace, Constantinople, on 21 September 1866 to Georgian HH Hayranidil Kadın Efendi ( Kars, 2 November 1846 – Ortaköy Palace, Constantinople, 26 November 1898 ), and had two children.

The Earl of Derby, Prime Minister 1852, 1858 – 59, 1866 – 68

Charles Erdman ( 1866 – 1960 ) advocated apostolic authorship and wrote that only the Apostle John fits the image of the author derived from the text.

#** Marie Laetitia Eugénie Catherine Adélaïde Bonaparte ( 1866 – 1926 )

Le déjeuner sur l ' herbe, ( right section ), with Gustave Courbet, 1865 – 1866, Musée d ' Orsay, Paris, France | Paris

In April 1866 he nominated Henry Stanbery to fill the vacancy left with the death of John Catron, but the Republican Congress eliminated the seat to prevent the appointment.

* 1866 – Herbert Henry Dow, American chemical industrialist ( d. 1930 )

Furthermore, Davis accused Gould of having misrepresented a study by Henry H. Goddard ( 1866 – 1957 ) about the intelligence of Jewish, Hungarian, Italian, and Russian immigrants to the U. S., wherein Gould reported Goddard's qualifying those people as " feeble-minded "; whereas, in the initial sentence of the study, Goddard said the study subjects were atypical members of their ethnic groups, who had been selected because of their suspected sub-normal intelligence.

According to historian and Herald for Wales, Major Francis Jones, 1908 – 1993, the introduction of the recipe can be attributed to Captain Henry Lewis Edwardes 1788 – 1866.

* December 23 – William Henry Harrison, English cricketer ( b. 1866 )

** Henry Daglish, Premier of Western Australia ( b. 1866 )

# Henry Coppée ( 1866 – 1875 ), soldier, author, and engineer

In Cathay and the Way Thither, 1866, Henry Yule writes:

* Herbert Henry Dow ( 1866 – 1930 ), founder of Dow Chemical Company

Henry Bergh ( August 29, 1813 – March 12, 1888 ) founded the American Society for the Prevention of Cruelty to Animals ( ASPCA ) in April, 1866, three days after the first effective legislation against animal cruelty in the United States was passed into law by the New York State Legislature.

Henry Nicholson, rector from 1835 to 1866, was also active in repairing the abbey church — as far as he could, and in uncovering lost or neglected Gothic features.

* Henry Watkins Allen, ( 1820 – 1866 ), Confederate Army officer, was born in Prince Edward County.

* Henry William Connor ( 1793 – 1866 ), born near Amelia Court House, United States Congressman from North Carolina

After his death in 1866, it was taken over by his son-in-law Henry Maudsley who ran it until 1874.

It was named for Henry Bolton, who along with Donal McRae, opened a general store in Alpena in 1866.

* Henry Francis Hope Pelham-Clinton-Hope, 8th Duke of Newcastle-under-Lyne ( 1866 – 1941 ), second and youngest son of the 6th Duke

A number of well-known people were educated at Dumfries Academy, among them Henry Duncan, founder of the world's first commercial savings bank, Sir James Anderson, who captained the SS Great Eastern on the Transatlantic telegraph cable laying voyages in 1865 and 1866, James Matthew Barrie, author of Peter Pan, missionary Jane Haining, international diplomat Alexander Knox Helm, John Laurie, actor ( Private Fraser in Dad's Army ), artist Robin Philipson, singer John Hanson, Alex Graham, cartoonist best known for the Fred Basset series and Jock Wishart, who in 1998 set a new world record for circumnavigating the globe in a powered vessel.

Henry XXII of Reuss Elder line is notable among the more modern princes of this house for his enmity to Prussia, which he opposed in the Austro-Prussian War of 1866, when the Prussian troops occupied his domain.

* Henry Cantwell Wallace ( 1866 – 1924 ), U. S. Secretary of Agriculture, father of Henry A. Wallace

By September 1866 construction had advanced to the point where the Board of Trade inspector Captain Henry Tyler could make an initial inspection and report.

Between 1862 and 1866, usually with Henry Tracey Coxwell as his co-pilot, Glaisher made numerous ascents in order to measure the temperature and humidity of the atmosphere at its highest levels.

From 1841 Henry Littleton assisted him, becoming a partner in 1861, when the firm became Novello & Co., and, on JA Novello's retirement in 1866, sole proprietor.