A Dictionary of the English Language, sometimes published as Johnson's Dictionary, was published on 15 April 1755 and written by Samuel Johnson. It is among the most influential dictionaries in the history of the English language.

There was dissatisfaction with the dictionaries of the period, so in June 1746 a group of London booksellers contracted Johnson to write a dictionary for the sum of 1,500 guineas (£1,575), equivalent to about £260,000 in 2022. Johnson took seven years to complete the work, although he had claimed he could finish it in three. He did so single-handedly, with only clerical assistance to copy the illustrative quotations that he had marked in books. Johnson produced several revised editions during his life.

Until the completion of the Oxford English Dictionary 173 years later, Johnson's was viewed as the pre-eminent English dictionary. According to Walter Jackson Bate, the Dictionary "easily ranks as one of the greatest single achievements of scholarship, and probably the greatest ever performed by one individual who laboured under anything like the disadvantages in a comparable length of time".

Samuel Johnson (18 September 1709 [OS 7 September] – 13 December 1784), often called Dr Johnson, was an English writer who made lasting contributions as a poet, playwright, essayist, moralist, critic, biographer, editor and lexicographer. He was a devout Anglican, and a committed Tory. The Oxford Dictionary of National Biography calls him "arguably the most distinguished man of letters in English history". James Boswell's Life of Samuel Johnson was selected by Walter Jackson Bate as "the most famous single work of biographical art in the whole of literature".Born in Lichfield, Staffordshire, he attended Pembroke College, Oxford until lack of funds forced him to leave. After work as a teacher, he moved to London and began writing for The Gentleman's Magazine. Early works include Life of Mr Richard Savage, the poems London and The Vanity of Human Wishes and the play Irene. After nine years' effort, Johnson's A Dictionary of the English Language appeared in 1755 with far-reaching effects on Modern English, acclaimed as "one of the greatest single achievements of scholarship". Until the arrival of the Oxford English Dictionary 150 years later, Johnson's was pre-eminent. Later work included essays, an annotated The Plays of William Shakespeare and The History of Rasselas, Prince of Abissinia. In 1763 he befriended James Boswell, with whom he travelled to Scotland, as Johnson described in A Journey to the Western Islands of Scotland. Near the end of his life came a massive, influential Lives of the Most Eminent English Poets of 17th and 18th centuries.

Tall and robust, he displayed gestures and tics that disconcerted some on meeting him. Boswell's Life, along with other biographies, documented Johnson's behaviour and mannerisms in such detail that they have informed the posthumous diagnosis of Tourette syndrome, a condition not defined or diagnosed in the 18th century. After several illnesses, he died on the evening of 13 December 1784 and was buried in Westminster Abbey. Thereafter he was increasingly seen to have had a lasting effect on literary criticism and even claimed to be the one truly great critic of English literature.