Lewis Hertslet (1787–1870) was an English librarian and editor of state papers.
He was the eldest son of Jean Louis Pierre Hertslett (or Hiertzelet), a Swiss king's messenger who had migrated to Great Britain, born in November 1787.
[1] He entered the Civil Service, and on 5 February 1801 was appointed sub-librarian in the Foreign Office; and on 6 January 1810 librarian and keeper of the papers.
[2] Hertslet was one of the two secretaries of the lords justices in England while George IV was absent in Hanover in 1821.
His youngest son, Edward (1824–1902) succeeded him as librarian at the Foreign Office.