During the Autumn of Terror hundreds of letters were sent to the police and local press purporting to be written by the Whitechapel fiend. Most of them were deemed to be fakes written by either newspaper men trying to start a story or fools trying to incite more terror. Many Ripperologists believe them all to be hoaxes. Other experts believe some (specifically the Dear Boss letter, Saucy Jacky postcard, and From Hell letter) are genuine. A select few have been reproduced below.

'Dear Boss' letter

Received on September 27th, 1888 at the Central News Agency, this letter was originally believed to be just another hoax. Three days later, the double murder of Stride and Eddowes made them reconsider, especially once they learned a portion of the latter's earlobe was found cut off from the body, eerily reminiscent of a promise made within the letter. The police deemed the "Dear Boss" letter important enough to reproduce in newspapers and postbills of the time, hoping someone would recognize the handwriting.

A postcard received at the Central News Agency on October 1st, making direct reference to both the murders and the "Dear Boss" letter, is believed to have been written by the same hand. It is reproduced below.

Whether or not the letter is a hoax, it is the first written reference which uses the name "Jack the Ripper" in reference to the Whitechapel murderer.