For the past 80 years, Batman has been a staple of comic book culture and has remained seeped in pop culture over all, remaining among the most recognizable superheroes around. Even his adversaries end up with similar fates, with tons of his biggest foes still circulating around the comic world all these years down the line or ending up in some sort of media alongside the Caped Crusader. Sometimes, though, these foes can end up falling into obscurity, even though we all know the likes of Mister Freeze or Two-Face, there's one that often ends up overlooked a lot.
While Batman has a lot of foes that could be considered "obscure," like Condiment King or Victor Zsasz, one that seems to never get mentioned is one that is probably too dark to ever return and one that has potentially a very disturbing hidden meaning. Ray Salinger, AKA Birthday Boy, is a serial killer with a penchant for young girls.
Ensnared in Gotham's criminal underworld, Salinger is a muscular man who would take young girls as payment from Mayor Cobblepot to kill people the later didn't like. He would take his victims to a room decorated like a little girl's room and, while doning a burlap sack and a party hat, would tell his victims, to which he would always refer to as Amanda, to make a wish before then butchering them and tossing them into the basement of the abandoned Arkham Manor.
The reason behind this specific penchant towards girls is linked to his first victim, 15-year-old Amanda Grant. There's no reason given as to why he killed her, which frankly, makes his character even more disturbing.
Turning to a fellow serial killer within the Batman universe, Victor Zsasz was given a backstory of personal fortune, family death, deep depression, gambling addiction, and a jaded view of existance, believing that he would be doing victims a favor by riding them of their existance, as he sees life as meaningless. We get no such backstory for Salinger. What we know from his first appearance in 2012's Batman: Earth One #1 is the extent of what we know now in 2025.
While it would be cool to see Birthday Boy return in some capacity, it's also something we can see a hard sell for DC to greenlight, the character is arguably more mentally distrubed than Zsasz, his motives are impossible to spin, and many of Batman's foes have had a level of humanity to them that Salinger simply can never have. Perhaps in a grimdark Batman tale, but it's been over a decade and DC's never as much mentioned the birthday-themed killer.