Samuel Ayscough (1745–1804) was a librarian and indexer, known as 'The Prince of Indexers'.
Ayscough was a cataloguer in the British Museum in the late 18th century, and spent two years working on a catalogue of the manuscript collection. He accumulated over 20,000 slips of paper in compiling this, which he published as A Catalogue of the Manuscripts preserved in the British Museum Hitherto Undescribed (London, 1782).
Ayscough is also remembered as the writer of the first concordance to Shakespeare. Entitled An Index to the Remarkable Passages and Words Made Use of by Shakespeare; Calculated to Point out the Different Meanings to Which the Words are Applied, it was published by John Stockdale in 1790.
He also compiled a General index to the fifty-six volumes of the Gentleman's Magazine from its commencement in the year 1731, to the end of 1786. He died in 1804 in the British Museum.