Henry Sidgwick was an English utilitarian philosopher and economist. He was the Knightbridge Professor of Moral Philosophy at the University of Cambridge from 1883 until his death, and is best known in philosophy for his utilitarian treatise The Methods of Ethics. He was one of the founders and first president of the Society for Psychical Research and a member of the Metaphysical Society and promoted the higher education of women. His work in economics has also had a lasting influence. In 1875, with Millicent Garrett Fawcett, he co-founded Newnham College, a women-only constituent college of the University of Cambridge. It was the second Cambridge college to admit women, after Girton College. In 1856, Sidgwick joined the Cambridge Apostles intellectual secret society.

Henry Slesar was an American author, playwright, and copywriter. He is famous for his use of irony and twist endings. After reading Slesar's "M Is for the Many" in Ellery Queen's Mystery Magazine, Alfred Hitchcock bought it for adaptation and they began many successful collaborations. Slesar wrote hundreds of scripts for television series and soap operas, leading TV Guide to call him "the writer with the largest audience in America."

Charles Henry St. John Cooper was a prolific English novelist of school and adventure fiction. He wrote thousands of stories for several Amalgamated Press papers, sometimes under the pen name Mabel St. John. He is perhaps best known for creating, in 1908, the character Pollie Green, considered the "most popular, though not the first, in a series of irrepressible schoolgirl heroines". According to his son, he also wrote many "authorless" Sexton Blake stories for the Union Jack. His novel Sunny Ducrow was adapted into a 1926 film, Sunny Side Up.

Colonel Henry Steel Olcott was an American military officer, journalist, lawyer, Freemason and the co-founder and first president of the Theosophical Society.

Henry Sweet was an English philologist, phonetician and grammarian.

Henry Sydnor Harrison (1880–1930) was an American novelist, born in Sewanee, Tenn. He graduated from Columbia in 1900, and received an honorary A.M. from the same university in 1913. In 1914, he was elected a member of the National Institute of Arts and Letters. He wrote under the pen name "Henry Second," and made contributions to The Atlantic Monthly and other magazines. Novels written by him include Queed (1911) and V.V.'s Eyes (1913), which were very well received. Other works include Angela's Business (1915), When I Come Back (1919), Saint Teresa (1922), and Marriage (1923), a volume of short stories. Harrison also wrote a story, called "Miss Hinch", where a daring criminal and the lady after her make their way through New York City streets at midnight.

Henry Thew Stephenson (April 22, 1870 – 1957) was a teacher and writer.

Henry Thomas Buckle was an English historian, the author of an unfinished History of Civilization, and a strong amateur chess player. He is sometimes called "the Father of Scientific History".

Henry Thomas Hamblin was an English mystic and New Thought author.

Henry Timrod was an American poet, often called the "Poet of the Confederacy".