It is very difficult to talk about the late Victorian period and NOT mention Jack the Ripper. This 6 page PDF covers how to use Jack in your games and assumes that he will be an adversary of the Characters. Two possible means of link Jack to the PCs as a nemesis are discussed. Some detail is given on the public and police reaction to the Ripper case. Some basic d20 crunch is given to help move the players along.
Stats are given for Jack the Ripper (d20 Modern) and some ideas are given based on the level of magic in your games.
The text of the "Jack the Ripper letters" are reproduced.
While I think this is a good starting effort a lot more could have been done. A lot more. For example a time-line of the Ripper case should have been included and the names of his victims. Also a map of the killings would have been extremely helpful. While all of this is readily available, that is also the exact reason why it should have been included.
As it stands this is just a PDF of a potential threat to the PCs with not much in it that says it is Jack the Ripper.