There is also the 2011 letter from Osama that was found after the raid on his compound in Pakistan, which I doubt is a real letter, given it praises Obama, and expresses a concern for climate change, of all things, and is more likely to have been written by Obama than Osama.
https://www.dni.gov/files/documents/ubl2016/english/To%20the%20American%20people.pdf