By Nationality:

French
Delacroix, Eugène
Géricault, Théodore

Swiss
Fuseli, Henry

German
Friedrich, Caspar David
Overbeck, Johann Friedrich
Schwind, Moritz von

British
Constable, John
Palmer, Samuel
Turner, J.M.W.

American
Allston, Washington
Cole, Thomas

Spanish
Goya, Francisco