Question:

Who wrote II Kings?

Answer:

I Samuel, II Samuel, I Kings and II Kings are actually one long book which became divided into four parts. Scrolls can only hold so much before they become unwieldy. The books are thought to be the work of a series of prophets. Such makes the most sense since it covers a large period of history.

This statement is probably referring to I Samuel, II Samuel

"Now the acts of King David, first and last, indeed they are written in the book of Samuel the seer, in the book of Nathan the prophet, and in the book of Gad the seer" (I Chronicles 29:29).
This statement is probably referring to I Kings:
"Now the rest of the acts of Solomon, first and last, are they not written in the book of Nathan the prophet, in the prophecy of Ahijah the Shilonite, and in the visions of Iddo the seer concerning Jeroboam the son of Nebat?" (II Chronicles 9:29).

"The acts of Rehoboam, first and last, are they not written in the book of Shemaiah the prophet, and of Iddo the seer concerning genealogies? And there were wars between Rehoboam and Jeroboam all their days." (II Chronicles 12:15).

"Now the rest of the acts of Abijah, his ways, and his sayings are written in the annals of the prophet Iddo" (II Chronicles 13:22).

It isn't a complete list because it only takes the accounts up to Abijah. There is a good argument that Jeremiah was involved in the writing of at least parts II Kings since it contains many details that he was directly familiar with (compare Jeremiah 52 and II Kings 24-25) and ends in his time. It is possible that Jeremiah served as editor for all four books.