I guess this thread is a bit of misnomer since you're not asking about the classic psych books but the ones I would recommend:
Esquirol, Etienne. (1845) Des Maladies Mentales.
Esquirol was one of the fathers of French Alienism, the precursor to modern psychiatry. In this text he gives some fantastic descriptions of various extreme mental states, many of them likely toxic/organic in origin, and classifies mental disorder into mania, demonomania, lypemania, fury, epilepsy, dementia, and idiocy.
Kraepelin, Emil. (1920) Manic Depressive Insanity and Paranoia
This text has some of the best descriptions of manic and depressive episodes, charts the life course of mood disorders in the pre-lithium era, and gives wonderful descriptions of different sorts of mixed states. One of the remarkable things is that many patients went for years without episodes despite medication, periods of remission that today would be regarded as because of the medication.
Bleuler, Eugen. (1911/1950) Dementia Praecox or the group of schizophrenias.
This text first coined the term schizophrenia and Bleuler masterfully described the psychological aspects of the disorder regarding not delusions and hallucinations but though disorder and loosening of associations as the sine qua non of the schizophrenias. He was heavily influenced by Freud and Janet, and a dynamic interpretation of schizophrenia is at the heart of his description of schizophrenia which became the reigning conception of schizophrenia in North America until 1980.
Hamilton, Max. (1980) Fish's Clinical Psychopathology
Unfortunately out of print, and I lost my copy 🙁 this wonderful text, Frank Fish introduced the tenets of descriptive psychiatry from Germany to an English speaking readership. Really fantastic, especially in terms of the psychopathology of schizophrenia, and very, very funny!
Friedmann, Claude and ***uet, Robert (Ed.) (1982) Extraordinary disorders of human behavior.
This is a really great book for the description of the uncommon psychiatric syndromes including Munchausen's, Capgras syndrome, Cotard syndrome, De Clerembault syndrome, the cycloid psychoses, autoscopia, ganser syndrome, Koro, amok etc. Written in the early 80s there are some laughable psychodynamic interpretations for some of the syndromes, but it is nonetheless a good read
von Krafft-Ebing, Richard (1894) Psychopathia Sexualis
Despite some unenlightened views of human sexuality, herein are some of the richest descriptions of the vast array of sexual behavior ever described and remain unrivaled to this day. The precise approach taken by von Krafft-Ebing is impressive in itself. The cases are really interesting, you can just dip in and out of it. And the most sexually gratuitous bits are in latin.
Jaspers, Karl. (1913) General Psychopathology
This is the one of the most important and least read texts of 20th century psychiatry. Because it's actually really long and difficult but there are some great descriptions of obsessions and analysis/critique of Freud. Again one to dip into, probably too heavy going to read in its entirety. Every psychiatrist should have these books on their shelves if only to look intellectual!
will add more later!