Wikipedia states :'Gallus Mag (real name unknown) was a 6-foot-tall female bouncer at a New York City Water St. bar called The Hole in the Wall in the early 19th century, who figures prominently in New York City folklore. Herbert Asbury's book The Gangs of New York thus describes her:
"It was her custom, after she’d felled an obstreperous customer with her club, to clutch his ear between her teeth and so drag him to the door, amid the frenzied cheers of the onlookers. If her victim protested she bit his ear off, and having cast the fellow into the street she carefully deposited the detached member in a jar of alcohol behind the bar…. She was one of the most feared denizens on the waterfront and the police of the period shudderingly described her as the most savage female they’d ever encountered." 
A composite female street gangster character based on her, Sadie the Goat, and Hellcat Maggie, is played by Cara Seymour in the Martin Scorsese film Gangs of New York.'
It is, of course, interesting that the original went by the cognomen Gallus, given that the Galli were the cross-dressed self-castrated priests of Cybele in Classical Rome. (Roman citizens were originally forbidden to become Galli, but it was legalized under Claudius.) There is a poem by Catullus on this theme, and the legend of Attis, which I really must translate sometime.
(It's also interesting that Gallus is also the word for a cockerel, and that the goddess Bahuchara Mata, worshipped by many self-castrated woman-identified hijra in South Asia, rides on a cockerel. But heaven forfend that anyone suggest that it is not only in C21 that trans people have had an international culture.)
Anyway, I find myself speculating that the Hole in the Wall's Gallus was a trans woman - six foot is a very great height for a cis woman in the early C19 - and it would explain the possible classical reference of her name, wouldn't it? An educated trans woman reduced to being a bouncer in a bar by bigotry and finding in the criminal underworld the acceptance denied her elsewhere in mid-C19 society. And yes, this is something I shall probably write a long narrative poem about at some point.
In the mean time, I think it desperately funny to speculate that through sheer cluelessness and failure of imagination, a major transphobe is unironically dressing herself up in a trans woman's name. Poor silly person.