I'm putting together a working list of "castmembers" for my Jack the Ripper scenario. PCs and NPCs will be drawn from this list. From this list I can see at least 6 factions that might be involved in the situation:

the Street People
the Literati
the Vigilance Committee
the Authorities
the Russian Agents
the Occultists

Some figures would overlap, creating interesting dynamics. Francis Thompson was both a poet and a bum, for example. In my plot the Russians might be on the tale of Nicholas Vassily, who may have committed Ripper-like crimes in Paris. In my version of events he also stirred up trouble in a city of the Russian Empire.