William Stetson Merrill

William Stetson Merrill (1866 – 1969) was an American librarian at Newberry Library, who also contributed to the fields of library classification and history. He was the author of A Code for Classifiers in the period 1912 to 1939, and was connected to the American Library Association. He was also a scholar on Vinland.

A Code for Classifiers Merrill's 1928 book A Code for Classifiers: Principles Governing the Consistent Placing of Books in a System of Classification is still under scrutiny in the field of information studies. It is "essentially a description of the problems in classification arguing the need for a classifier's code, a code that transcended individual classification systems". A second edition was released in 1939. The article The Vinland Problem Through Four Centuries (1935) is a review of available theories about Thorfinn Karlsefni's voyages in the Saga of Erik the Red.

Honours Merrill was an honorary member of the Knights of Columbus and the Chicago Library Club.