Created at the tail end of the Cold War by Jims Starlin and Aparo and inker Mike DeCarlo, the KGBeast was pretty much that - a beast. A cold, unflinching monster of a man who was seemingly unstoppable as he sets upon a mission of killing the ten names closest to the United States STAR Wars missile defense program. Check out what happens when Batman underestimates the lengths the Beast will go to to finish a job...
After the Cold War ended, the KGBeast kept coming back, now just as a traditional supervillain doing money-making schemes or often as a henchmen working for other criminals. He was still one tough son of a gun.
Firefly was a one-off Batman villain from the early 1950s who used optical illusions against Batman (including making it look like things were on fire). Years later, Chuck Dixon and Graham Nolan awesomely revamped him in Detective Comics by making him an ACTUAL arsonist.
So along with his great new design, Firefly became a mainstay of Batman's Rogues Gallery, one of those guys who always hangs around the periphery as a nice villain you can use if you ever need a villain. And always up for teaming up with other villains. He is to Batman like the Shocker is to Spider-Man.
Holiday is a mysterious serial killer who is at the heart of the acclaimed Batman story A Long Halloween (by Jeph Loeb and Tim Sale). A killer is going around Gotham killing people at holiday times and leaving a token of the holiday behind after the killing.
In the end, we honestly do not know who the Holiday killer is for sure, as two people take credit for the killings (SPOILERS FOR A STORY FROM MORE THAN FIFTEEN YEARS AGO!) - Alberto Falcone, the youngest son of Carmine Falcone, who publicly confessed to the crimes, said he began killing to take revenge on his father for never taking him seriously (and cutting him out of the family business) and Gilda Dent, the wife of Harvey Dent, who privately confessed while talking to herself and burning evidence at the end of the story, explaining that she began killing to wipe out the Falcone crime family so her husband would stop obsessing over them and settle down with her. In the latter scenario, Gilda alleges that she stopped the killings after the first few and presumed that Harvey had taken over for her (the only undisputed killings are the last two, which are definitely by Harvey after he becomes Two-Face).
Owlman is a member of the Crime Syndicate, who are the evil opposites of the Justice League. Owlman, naturally, is Batman's opposite.
Owlman is Thomas Wayne, Jr. His mother and younger brother, Bruce, were killed by a police officer. His father, Thomas Wayne Sr., became the chief of police in Gotham and Thomas became a villain to oppose his father, who he blames for the death of his mother and brother. Owlman loves the fight, so he actually secretly funds rebels to the Crime Syndicate control of their planet, just so he has someone to fight.
While on the Justice League's Earth, he figures out that the way that this world works, the Crime Syndicate inherently cannot win. He comes to this realization in a great moment where he comes across the graves of this world's Thomas and Martha Wayne and realizes that he can never gain vengeance on his father on this world...
Anarky (created by Alan Grant, Norm Breyfogle and Steve Mitchell) is an interesting case because he is really more of an anti-hero than anything, as he is a teenager who embraces the ideals of anarchy and decides to become a vigilante to have his voice heard.
That said, his methods are extreme enough that Batman can never accept Anarky as a hero, so I guess he belongs in the villains section. He DOES practically kill this dude just for being a hypocritical drug addict...
Anarky later had his own SERIES by Grant and Breyfogle. Sadly, once Grant was finished at DC, so, too, was Anarky for the most part (at least Grant's nuanced approach to the character).