How has this show even been allowed to air, without a substantial royalty cheque being whisked to Alan Moore?
I'm no copyright lawyer, but its pretty obvious that Penny Dreadful is more than just a little derivative of League of Extraordinary Gentlemen. Whilst some of the literary characters are exempt from copyright law (Hence Moore's original appropriation), and Character-mashing has been done plenty of times before, this seems deliberately built on the back of League...
The analogues are far too similar; retired colonial African Hunter as leader (check!), supernatural female high class courtesan (check!), American gunslinger as support (check!), Dorian Grey (Check!!)....
Did Showtime originally attempt to get the rights for League, and fail (and if so, how have they avoided the litigious ramifications of derivative work), or have they tried to present the works as unconnected, and hope no one notices?