Ax Crazy Psychologically unstable and capable of extreme violence. Yep.
Back From the Dead A Black Lantern ring resurrected him during Blackest Night and he terrorized Catwoman as a flying zombie. Shit was so cash.
Best Served Cold Nearly all of Roman's adult life is one revenge plot after another directed at his parents, Bruce Wayne, Batman, Catwoman...Catwoman especially. He's dedicated.
Big Bad Particularly at his height of power as Gotham's ruling crime lord.
Card Carrying Villain One of Batman's more ambitious Rogues. Was also approached by Deathstroke to join Luthor's Society (although that fell through).
Chronic Backstabbing Disorder Everyone who works for him eventually ends up being backstabbed.
Cold Blooded Torture His hobby.
Complete Monster He is an irredeemable bastard who knows it and enjoys it.
Corrupt Corporate Executive As CEO of Janus Cosmetics, he pushed through an untested line of waterproof makeup in attempt to save the company after the previous line had flopped. The makeup disfigured hundreds of women and resulted in over 400 lawsuits in one week. After being bought out by Wayne, he gave up and pursued a successful career in crime lording.
Creepy Sexy Let me just leave this here...
Crowning Moment of Awesome The end of War Games, especially once he's used Gotham's criminal population as cannon fodder and has stormed Oracle's clocktower.
Disproportionate Retribution All of his attempts at revenge ever.
Dressed to Kill/Man of Wealth and Taste/Sharp Dressed Man Always wears a suit and tie (even as a child).
Evil Counterpart To Bruce Wayne. They both came from wealthy families, met as children, and their parents both died in unnatural circumstances, although Roman killed his.
Evil Has a Bad Sense of Humor Type 2: especially sick and twisted. After his death, one of his former goons is seen complaining that he couldn't stand listening to Black Mask and his unfunny jokes. Roman's responded to accusations that he is sick and twisted with a laugh and a "You have no idea". He's also cracked jokes about his personel having weak stomachs because they couldn't handle watching him torture people (which he refers to as "recreational hours"). He's joked about past tortures ("Like I said, you got heart, kiddo. What say we cut you open and get a look at it? Naw, don't worry. I'm kidding. Just reliving a fond memory."). Moreover, he's joked with people as he's torturing them ("now c'mon, Maggie. Be a big girl and swallow your medicine...through the teeth and over the gums...watch out stomach, here it comes..."). And he uses JK and LOL.
Evil is Stylish Like most of Batman's Rogues Gallery, he's got a theme and goes about his plans in roundabout and often ridiculous ways.
Eye Scream Owns a metal device that holds the eyelids open. Forced Catwoman's sister to eat her husband's eyeballs. Tortured a man with a pizza cutter and cayenne pepper, focusing on the eyes.
Faceless Goons His original gang (which he referred to as his 'army') was called the False Face Society because they all wore masks.
Flaying Alive He wants to turn Red Hood's skin into a sweatervest, and there's nothing at all to suggest it's something he hasn't done before.
Forced to Watch Forced Catwoman's sister, Maggie, watch as he tortured her husband to death. Enjoys making his hired help watch him at work. He also has created at least one videotape of a torture session of one of Catwoman's friends, which he intended to send to her.
Glass of Chianti He's often seen relaxing with a glass of scotch (or a martini).
Hair Trigger Temper He murders people who annoy him. Is also set off by hypocrites, bad manners, and costumed vigilantes.
Hannibal Lecture Most notably to Stephanie Brown while torturing her.
Hero Killer Tortured Stephanie Brown aka Spoiler aka Robin to death.
High Octane Nightmare Fuel Torture, torturing a teenage girl, murder, stalking, selling drugs to little kids, disfiguring his ex-fiancee's face and forcing her to be his queen, his face, the lengths at which he goes for revenge, forcing people to cannibalize their spouses...everything he does.
If I Can't Have You Disfigures his ex-fiancee Circe so she can be his queen. Was so obsessed with her that after she committed suicide, he kept around a mannequin named after her which he talked to and treated as a real person.
Karmic Death/Killed off For Real Shot in the face by Catwoman.
Lack of Empathy And the inability to relate to others in a healthy manner.
Mind Control Device Implanted one of the Mad Hatter's mind control chips directly into Killer Croc's brain.
Mind Rape The torture of Maggie Kyle drove her to become an instituationalized mute.
Moral Event Horizon Burning his parents alive while watching from the bushes. Sure, they weren't very nice and, in fact, they were neglectful parents, but he wouldn't have inherited the multilmillion dollar company if he'd cut ties. And he spent time at their funeral wondering if the company had tapped the lucrative market of morticians' cosmetics.
Murder is the Best Solution Except when it comes to Catwoman.
Nightmare Face His face is a black skull without lips, a nose, eyelashes, or hair.
Obviously Evil Because the skull head isn't a dead give away or anything :|
Revenge by Proxy All the Wayne employees he facially mutiliated and then murdered because Bruce Wayne made him lose face by buying out his company, Janus. Later, stealing Catwoman's family and torturing/killing them because she stole diamonds from him: "You hurt me, you stole from me. So I hurt YOU, and I stole from you. I just stole a lot deeper than you were willing to go."
Rich Bitch The Sionis family.
Rogues Gallery Batman's.
Skull for a Head A black one.
Take a Level in Badass He started off as a villain obsessed with masks and had a crippling psychosis.
Trash Talk He loves to hear himself talk. Every fight he has is full of trash talking his opponent, listing off why they suck and so on. When he comes back as a flying space zombie, Catwoman even remarks that he has the same trash talking attitude as a corpse as he did alive.
Torture Always Works All the information he's extracted from people has been correct.
Torture Cellar He's shown to have multiple torture chambers: in his home (he's had several homes) and in the sub basement out of which he runs his criminal enterprises (again, he's had several). One had an Iron Maiden. Even his safehouse had a crude torture room.
Torture Technician He loves torture even more than he loves being a crime lord.
Villain Team Up Long history of having hired or worked with other villains, including: Black Spider, Scarecrow (very briefly), Mr. Freeze, Mad Hatter, and Croc (although 'enslaved' would be far more appropriate).
You Have Outlived Your Usefulness Everyone who works for him ends up here, eventually.