The Cotton or Cottonian library is the library compiled by Sir Robert Bruce Cotton (1571 - 1631), antiquarian and bibliophile. Cotton's library was just that: the books, manuscripts, coins and medalions he had collected in his personal estate. Cotton amassed his collection by gathering up the books and artifacts freed up by the dispersal of the monasteries by Henry VIII. Consequently, his collection is the single greatest resource of literature in Old English and Middle English we have. We owe Beowulf, Pearl, and the Lindisfarne Gospels to Cotton's collection.

The leading scholars of the era came to use his library. Francis Bacon, Walter Raleigh, James Ussher and others came to use his works. Upon the foundation of the Bodleian Library, he made a substantial contribution.

His grandson, Sir John Cotton, gave the rest of the library to the nation of Great Britain. The library went first to Essex House and then to Ashburnham House. In 1731, there was a fire in Ashburnam House, and many manuscripts were lost, while others were badly singed. Fortunately, copies had been made of some of the manuscripts, but by no means all, of those works that were lost. The Cotton library is now part of the British Library.

Robert Cotton had organized his library according to the corner and shelf of a book. He had busts of the various Caesars in his library, and his scheme worked by Caesar-Shelf letter-Volume number from end. Thus, the two most famous of the manuscripts from the Cotton library are "Cotton Vitellius A xiv" and "Cotton Nero A x." In Cotton's own day, that meant "Go to the bust of Vitellius, top shelf (A), and count fourteen over," for the monstrarum librarum of the Beowulf manuscript, or "Go to the bust of Nero, top shelf, tenth book" for the manuscript containing all the works of the Pearl Poet. In the British Museum, these two priceless books are still catalogued by these call numbers..