University of Hawai'i
Uh: Jose Guadalupe Posada: My Mexico
This online exhibit from The University of Hawaii Art Gallery provides many images of Posada's woodcuts as well as insights into life in Mexico.
Brooklyn Museum
Brooklyn Museum: Urban Views: Realist Prints
"Urban Views: Realist Prints and Drawings by Robert Henri and His Circle" was on view at the Brooklyn Museum in 2006. This page shares various selected works from the permanent collection works on paper that made up the exhibit.
University of Hawai'i
Jose Guadalupe Posada: My Mexico
This online exhibit from The University of Hawaii Art Gallery provides many images of Posada's woodcuts as well as insights into life in Mexico.
ArtLex
Art Lex: Realism, or the Realist School
A straight forward description of realism in art, which has both a general and a specific meaning. Includes links to examples of nineteenth-century Realist art, including that of Courbet and Millet, two leading lights of the French...
Art Institute of Chicago
Art Institute of Chicago: Art Access: Nighthawks
View Hopper's famous "Nighthawks," along with contextual details and analysis.
Other
Brock University: Some Notes on Realism
This site talks about the different aspects of 19th-century realism. (From realist painting to literature)
Other
Electric Gallery: Abstract Realism Collections
This site includes the works of many realist artists. However, these paintings are more modern "abstract realism" rather than 19th century pieces.
Other
Richard R. Gandy Gallery of Realist Art
A gallery by Richard R. Gandy of Classical Realist art. Includes a good list of artists and has good images and information about works of art.