Aleister Crowley was a famous late 19th to early 20th century real life occultists were a lot of urban legends are about him.
He's actually featured in A Certain Magician Index as the Main Antagonist (The Guy in the Glass Tube.)
Carmella is a famous character in a vampire story and almost as famous as Dracula, and in her original story she was indeed a lesiban.
Victor is a hybrid of Dr Victor Frankenstein and Frankenstein's monster.
Jack is likely Jack the Ripper.
A Bit disappointed that Sherlock was nerfed to make our main protagonist look good.