Friedrich Noack, who wrote under the pseudonym F. Idus, (20 April 1858, Gießen – 1 February 1930, Freiburg im Breisgau) was a German cultural historian and author, who wrote several articles for the Künstlerlexikon (arts dictionary) Thieme-Becker.
In 1886, he translated Sebastian Brant's "Narrenschiff" and published it with his own illustrations.
For his work on the Germans in Rome in the 18th century, he devised a comprehensive archive of notes. On 18,000 slips of paper, it contains over 11,000 entries on artists active in Rome and their clients, usually in Gabelsberger shorthand, but also in newspaper cuttings and archive statements. Today the material is stored in the archive of the Bibliotheca Hertziana in Rome and is accessible online.