William Eaton Foster (June 2, 1851 - September 10, 1930) was an American librarian and author.

[1] He graduated from Brown University in 1876 and went to work as a librarian in the Hyde Park, Massachusetts Public Library.

[2] Foster attended the "Convention of Librarians" held during the 1876 Centennial International Exhibition in Philadelphia which is when the American Library Association was formed.

[3] In February 1891 he addressed the annual meeting of the Rhode Island Society of the Sons of the American Revolution which he joined as a charter member when it was founded the previous year.

Foster retired from the Providence Public Library after 53 years of service in February 1930 due to illness.