Hermann Hesse was a/an _______ writer.

Hermann Hesse was a German-Swiss writer. This means that he was a writer who was both German and Swiss. Hesse was born in Germany but later became a Swiss citizen. He wrote many famous novels, including "Siddhartha" and "Steppenwolf", which explore themes of spirituality and self-discovery. His writing style and themes were influenced by his experiences growing up in Germany and living in Switzerland. Therefore, the correct answer is German-Swiss.