Question: who wrote the tanach, the Nevi’im and Ketuvim?
Answer: Moshe rabainu Wrote the five Chumashim word by word from Hashem. The Nevi'im and Ketuvim were written by different prophets. Some of books were named after the Prophets who wrote them such as "Yirmiyahu" and "Yishayahu". For more detail: The Talmud, Baba-Batra 14b.