Cover, USA Comics #1 - Timely Comics (Marvel Comics) - August 1941. Cover feature: The Defender. Cover art by Jack Kirby (Pencils) & Joe Simon (Inks).

Source: http://www.comics.org/coverview.lasso?id=1580&zoom=4

Though this image is subject to copyright, its use is covered by the U.S. fair use laws because:

1. It illustrates an educational article about the comic book from which the cover illustration was taken.
2. The image is used as the primary means of visual identification of the article topic.
3. The image is from the historically significant debut issue of the series.
4. The use of the cover will not affect the value of the original work or limit the copyright holder's rights or ability to distribute the original. In particular, copies could not be used to make illegal copies of the book.
5. It is a low resolution image.
6. The image is only a small portion of the commercial product.
7. It is not replaceable with an uncopyrighted or freely copyrighted image of comparable educational value.