What is considered "famous" artwork?

Well, the general public isn't very familiar with most art. You can definitely do something like a Warhol, though. I read that book, loved it, and I would personally suggest Jean-Michel Basquiat because his work has a lot of the same atmosphere as Catch-22. It's hard because all of the artists I'm thinking of are household names to artists and illustrators, but not to Joe Shmo. Neo Rauch is a very famous painter who did WWII images, but known mostly by art students and illustrators.

It just came to me. I would highly recommend picking a piece by an expressionist. The most famous piece that you'll know is "The Scream" by Edvard Munch. A lot of the expressionists were reacting to the horrors and shock of the brutality of the first World War, and their art mirrors their strife and commentary on society in both what they painted and how they painted.

Hope this helps. If I think of anything else, I'll edit.

EDIT: I think your teacher is just trying to ensure that it's "credible" art, meaning that the artist an established reputation, and that it's not another student's work or just some really obscure thing. I have a feeling that if you put a work of art that isn't famous itself, but the artist is relatively well-known, then you'll be fine. If your teacher has a problem, you can show her/him information on the artist, the artist's achievements and the like.

EDIT: The themes of Warten auf die Barbaren are very close to Catch-22. The other works of his have imagery of a similar time period, and use the same kind of somewhat absurd imagery juxtaposition--putting images or thoughts together that are strange. But they don't have exactly the same imagery. I'd say go with Watching for the Barbarians if you like it. It's famous enough for me!

Warhol is very famous, so he would qualify as a famous artist. The assignment did not specify that it had to be pre-20th century art, right? So, I'd think any famous piece would do. Plus the book is 20th century, so it makes some sense.