In addition to being New Year’s Day, January 1st every year is also Public Domain Day, a celebration of artists and authors whose works are entering the “public domain” because the copyright protection of those works has expired.
Technically, no major works will actually enter the public domain in the United States this year (or in any year until 2019), thanks to a series of complicated changes to United States copyright law since 1978. But in many countries, copyright protection ends 70 years after the death of the artist or author. So in those countries at least, works by anyone who died in 1941 would have passed into the public domain on January 1, 2012.
Artists who died in 1941 include a number of important late 19th- and early 20th-century figures, such as Émile Bernard, Maximilien Luce, William McGregor Paxton, John Lavery, El Lissitzky, Alexei Jawlensky, and Robert Delaunay (left).
The VRC’s website has a Copyright page with more information and links to additional resources.
Please note that I am not a copyright lawyer, so my comments here should not be mistaken for legal advice. You should always consult a copyright professional if you have questions about whether or not a particular work is in the public domain.