If image collections on the Internet are any guide, much of his production was in the form of portraits that were a reliable source of income. Subjects ranged from family members to underclass people to royalty.
His artistic generation and Russian (not French or German) training yielded a consrvative, representational style. However, as best I can tell, he painted few if any works of classical subjects. One image below is of a religious nature.
This is Kramskoy's most famous painting. The subject seems to have been a lady of questionable repute.
He was about age 30 when this was painted.
Kramskoy was something of a court painter.
Click on this image to enlarge.
Not Kramskoy's usual subject matter. Note his treatment of rocks, sand and (morning?) sky.
An example of non-royal work.
Daughter of art patron Pavel Tretyakov (1832-1898).
Another unusual subject for Kramskoy, and very well done.