Ludwig

Origins:

Best I can tell, Ludwig was first described in an interview-style article printed by the National Police Gazette. I've seen the article, albeit not yet found a date for its printing:

A HUMAN BLOOD-SUCKER.

Strange Story of a German Tailor Who Has Developed a Dangerous Fondness for the Blood of Human Beings.

Ludwig Helreifel, a German tailor, living in Avenue B, between Second and Third streets, has acquired from his neighbors the singular name of "Blood-sucker." He not only indulges in animal blood as a tonic beverage, but expresses a preference for human blood, whenever he can get it.

This singular appetite was first made public by domestic troubles, which ended in a permanent separation between Helreifel and his wife; she, on her part, charging him with a dangerous inclination to gratify his unnatural thirst for blood at her expense. Helreifel is a diminutive, swarthy man. His head is very large, and covered with a shock of bristly, black hair that makes his head appear out of all proportion to the body. Hair seems to grow everywhere upon the man; even upon the tip of his nose there is a considerable tuft of hair. He is not a prepossessing man in appearance, and this, probably, has had something to do with prejudicing many against him. When asked by a reporter if it was true that he habitually drank human blood, he answered by asking if the reporter was acquainted with his former wife, Margueretha. On being assured that there was no such acquaintance, he then readily and freely told his story.

"Yes, it is true that I drink blood," said Helreifel, "and it is good for me. It is a good medicine. It makes me strong. The Germans eat blood sausages, and they all say it is good. But when I drink mine they say it is bad, and
THEY CALL ME BLOODSUCKER.
Now, what is the difference whether I take the blood before it is made into sausages or afterward? They make a fuss about nothing. But all the trouble came from that woman, Margueretha. She told all the women that I couldn't live without drinking the blood of some person. And the women, they told that story to everybody for the truth; but it is not so. She told them that I used to bite her arms in the night, when she was asleep, and then suck the blood. She made me so much trouble."

"But didn't you sometimes bite her arms?"
"Well, yes; I did bite her sometimes, but it was not in for the blood, although the blood from a person is better than that of an animal. It is just as much better as good wine is better than some common wine. If you would try it once you would see the difference. Human blood is richer, and it has a finer flavor."

When questioned as to how he came to acquire such a singular appetite, Helreifel said
IT BEGAN IN CHILDHOOD.
He was a very small, delicate child, and being the last survivor of six, his parents spared no trouble or expense to raise him. In Germany the poorer classes eat very little meat, while the children get almost none at all. But in Helreifel's case the doctor pronounced it poverty of the blood, and ordered a solid meat diet for the child. Even this did not have the desired effect and raw meat, and finally blood still warm from the animal, was given to him, Every morning his mother would take him to butcher's, where, for four pfenings, German money, a good drink of warm blood was obtained, the mother herself first tasting the blood to see if it was fresh and pure, or, as Helreifel expressed it, "not hum-bug-ged."

It this way he soon acquired an appetite for fresh blood. A cut or some similar accident when a boy at school first
GAVE HIM A TASTE OF HUMAN BLOOD.
Perceiving at once a difference, and that human blood was superior to animal, Helreifel acquired an actual appetite, a craving for the former. One reason for this preference was, he thought, because human for blood was very difficult to obtain.

At parting, Helreifel warned the reporter against heeding the slanders of his neighbors. "I like blood because it is good," he said, "but these foolish women think I am like that bat which sucks the blood from the people's feet at night until they are dead. I am not like that, and they tell lies about me when they call me Bloodsucker. I believe some of them think I would suck the blood from my own veins if I could not get it from another person, but that is humbug, I like a glass of human blood just as people like a glass of good wine. It brings a good feeling and makes me fresh and healthy. Good wine does the same thing; there is no difference."

There's mention online that Ludwig was written about previously in the New York Mercury. Supposedly a real Ludwig (full name: Franz Ludwig Helreifel) was born in 1824 in Germany, immigrating to Manhattan, but the dates don't wholly line up.

The New York Mercury only published between 1828 and 1832 (much too early for Ludwig to be immigrated, married, and well-known in Lower Manhattan), while National Police Gazette didn't start publishing until 1845 (at best, a 13 year gap in time to publish similar articles). Furthermore, National Police Gazette was a tabloid publishing sensationalized stories (fun fact: its last prints were about Hitler being gay and faking his own death, so its clearly best to take anything it prints with a grain of salt). So the liklihood of Ludwig actually being a real person seems highly doubtful.

The Ludwig urban legend rose to a more national prominence thanks to the 1928 book The Gangs of New York by Herbert Asbury, in which he was included:

Bismarck Hall and the House of Commons, nearby, were also the haunts of a Bowery character called Ludwig the Bloodsucker, who quaffed human blood as if it were wine. Ludwig was a very squat, swarthy German, with an enormous head crowned with a shock of bristly black hair. Huge bunched of hair grew out of his ears, and his unusual appearance was acentuated by another tuft which sprouted from the end of his nose.

The description comes quite 1:1 with the National Police Gazette article. Later stories would add details that Ludwig would wait for his drunken prey to stumble into the alleys before partaking of their blood.

All in all, the story reeks of anti-German sentiments, though it's hard to say for certain without finding the National Police Gazette article's printing year. Either way, Ludwig's story is firmly in fiction, not fact.