"Most people think Marv is crazy. He just had the rotten luck of being born in the wrong century. He'd be right at home on some ancient battlefield swinging an axe into somebody's face. Or in a Roman arena, taking his sword to other gladiators like him. They woulda tossed him girls like Nancy back then. "
Honor Before Reason: Will willingly and literally go to Hell to repay any and all kindness given to him.
I Call It Vera: His gun "Gladys", named after the harshest nun at his school. He feels it has almost lived up to its name.
Jack Bauer Interrogation Technique: "When I need to find something out, I just go and find somebody that knows more than me, and I go and ask them. Sometimes I ask pretty hard." Methods include sticking heads down toilets and driving along holding mooks' faces againts the asphalt.
Lightning Bruiser: Despite his size, Marv is just as quick and agile as he is strong. There are several instances where he takes down multiple opponents in a short span of time and even avoids getting shot.
A Man Is Not a Virgin: Heavily implied to have been one all his life due to his unattractive appearance and ultraviolent behavior, until The Hard Goodbye. Even claims to have been unable to buy a hooker due to his looks.
Not Good with People: Between his frightening appearance and mental instability Marv doesn't seem to do well with people, but he outright refuses to kill a wolf, instead knocking it unconscious, giving it a gentle pat and giving it a nice snack later.
Pay Evil unto Evil: He is deeply afraid of winding up as "a maniac [or] a psycho killer" and will only kill someone if, as Marv himself puts it, "I know for sure I ought to".
Shell-Shocked Veteran: Mentioned that he 'fought in a war', implied to be Vietnam, and shows an exaggeration of PSTD symptoms.
Unreliable Narrator: Has an unspecified "condition" which he admits makes him less than trustworthy. Although there is a very real possibility that he's hallucinating most of the unsavoury stuff shown, and might just be an insane murderer, later yarns do indicate that the events in The Hard Goodbye are likely very real.
Wouldn't Hit a Girl: Marv is really big on this, possibly due to his upbringing. The only times he breaks this is to spare Wendy from watching him torture Kevin to death, and killing a female sex-slaver in one short story (though it's ambiguous if the slaver is biologically female).
Badass: Aside from Miho, is likely the deadliest person in Basin City. He's only interest in the girl he saved and struck up a romance with.
Improbable Aiming Skills: He shoots sniper through the scope of his own rifle, using a regular handgun while in a dark room. Later, he kills an entire warehouse full of mooks before any of them have the chance to fire a single round.
Nice Guy: Amazingly nice, given the sheer ruthlessness and ugliness of the setting. It's notable that he gets one of the few truly happy endings in the entire comic series.
One-Man Army: Described as such in-universe. Wallace seems to be one of the most formidable fighters in the entire setting. While sheer numbers and firepower seems to give all but the most deranged of Sin City protagonists (Marv) some pause, all Wallace needs is a small amount of time to get some guns, and he is perfectly capable of dismantling a large part of a criminal organization, and is considered by their GenreSavvy leader to be "too costly" to seek revenge against.
Retired Badass: Ex-Navy SEAL to be specific. Apparently received the Medal of Honor in a high risk mission.
Hair of Gold, Heart of Gold: It's hard to tell because the comics are largely black and white, but Nancy Callahan is canonically blonde. A young woman working herself through law school by working as a topless exotic dancer off hours, she's probably the kindest and most innocent character in the comics (Word of God calls her "an angel" living in a Wretched Hive). She's aquainted with a lot of the major characters, who protect her from abusive or downright evil men out to hurt her.
May-December Romance: Subverted. She's in love with Hartigan but he refuses to sleep with her, because he's old enough to be her grandfather.
Nerds Are Sexy: She is very studious and is a fan of detective novels.
Sociopathic Hero: She does things that make even the more hardened of the girls of Old Town go "Yeesh!"
The Stoic: Miho has no expression on her face other than a deadly calm when she goes to work.
Tsundere: In Family Values, her softer side is shown when she cuddles up and goes to sleep on Dwight's lap and seems to have a very comfortable demeanor around him, in contrast to her earlier depictions where she is moments away from slicing him in half. Whether or not there is romance is up for debate. It hasn't stopped fans from Shipping the two of them. It's also a nod to her being frequently described as "catlike" in her mercurial attitudes and casual cruelty.
Always Save the Girl: Shows big time during the end of The Big Fat Kill, in willing to surrender Old Town in exchange for Gail. Unfortunately for the bad guys this is just a distraction serving to buy time for the rest of the Old Town girls to show up and unleash hell.
Anti-Hero: Type III. He once ventured into Type IV territory when he considered shooting a cop even though he wasn't sure he was clean or not. Generally, however, he's a normal guy who has been squicked out by the actions of both Marv and Miho.
Badass Bookworm: He is well-read, going by his knowledge of Spartan battle techniques and the fact that he apparently knows Latin. He was also a Pulitzer-worthy journalist at some point.
Batman Gambit: His plans often include a lot of manipulation but go off without a hitch.
Celibate Hero: He tries to avoid women earlier in the comics due to his bad prior break-up with Ava Lord, where he nearly drank himself into oblivion.
The Dulcinea Effect: Dwight is violently protective of women. Ava uses this against him in order to get rid of her husband Damien and get her hands on all his money.
Expy: Of Mike Hammer, though he lacks some of Hammer's more deranged tendencies.
Freudian Threat: Issues one against Jackie-Boy near the beginning of The Big Fat Kill
Dwight: You ever so much as talk to Shellie again — you even think her name — and I'll cut you in ways that'll make you useless to a woman.
Guns Akimbo: Dwight's weapons of choice are two 1911 pistols.
Would Hit a Girl: Though Dwight is violently protective of women, he is not above hitting them, whether because they have royally pissed him off (such as Ava) or because he needs to snap them out of hysterics (such as Gail).
The Old Town Girls
Belligerent Sexual Tension: Gail has this with Dwight. One minute they're madly in love, the other she's ready to blow his brains out if he does something stupid.
No Good Deed Goes Unpunished: Hartigan is rewarded for saving a girl from the worst kind of scum by being framed for her rape by the scumbag's even worse father and spending eight long years in prison.
Domestic Abuser: In at least one instance he gave Shelly two black eyes, and he punches her again after he and his friends barge into her apartment.
Fallen Hero: He was, apparently, at one point a hero cop who at some point was broken by Basin City and turned into the scumbag he is today. Frank Miller has stated he plans to do a comic detailing Jackie's fall at some point.
Not so Above It All: Mort falls head-over-heels for the destructive Ava while pursuing the investigation of the murderer of her husband. So much so, in fact, that Bob, the one who first got Mort to start pursuing women, wants more than anything to drag him from his destructive spiral before it is too late for him.
Evil Mentor: Sometime in the past, Cardinal Roark was approached by Kevin, a cannibal who murdered and dined on Old Town's prostitutes, believing he was devouring their souls. Convinced that Kevin was being spoken to by God, Cardinal Roark assuaged the boy's pangs of guilt and stashed him at the Roark family farm.
Sinister Minister: He earned much acclaim for his service as a field medic and priest during a war. Marv mentions that Roark could have parlayed this praise into becoming President, but he instead became a Cardinal. However, the Cardinal's influence is what allowed his brother to be become a Senator. He also joins in on Kevin's crimes, consuming parts of his victims' corpses.
Villain with Good Publicity: It's said he could've been president but chose to spend his life serving God instead. Even so, he's still influential and well-loved enough by the populace to get his brother elected senator.
Batter Up: The reason he can't produce more heirs is because he beat his previous wife to death with a bat.
Diabolical Mastermind: While he only appears in a few scenes he is the main reason why Roark Junior (AKA The Yellow Bastard) hasn't been arrested.
Heir Club for Men: He's obsessed with creating a legacy for himself through his son and descendants. The reason he's so vengeful towards Hartigan is because the old cop dashed his dreams of having Junior become President and nearly ended the Roark family line by shooting off Junior's genitals. These dreams permanently come to an end with his wife dead and Junior killed by Hartigan.
Karma Houdini: By the end of Hartigan's story. However, Hartigan notes that the Senator's plans for a legacy are dashed, and nobody left to fill his role in Sin City. And he'll be joining his brother and his son in Hell very soon.
Screw the Rules, I Make Them!: He was never even arrested for his wife's death even though (by his own admission) he left his fingerprints all over the scene.
Sleazy Politician: The Senator is well-connected in Sin City and will likely stay in office for a long time, but his chances of becoming President are nil.
Serial Killer: Initially only three victims of his were found, with Nancy Callahan being the attempted fourth, but Junior admits that he's killed hundreds of little girls.
Serial Rapist: Junior is a serial child rapist as well as a serial child murderer. When he gets his hands on Nancy eight years after his first attempt on her is thwarted by Hartigan, he states that Nancy is "too old for him," which says very disturbing things about him indeed.
Spoiled Brat: Hartigan calls him this many times and it seems to be true. He whines when he doesn't get his way and at one point, threatens a Mook that he will call his father if his Torture Cellar wasn't set up properly.
Ungrateful Yellow Bastard: Even after his dad saved his life and recovered his "equipment" with expensive surgeries, he still doesn't think that much of him.
Dragon-in-Chief: Is far more dangerous then Cardinal Roark in The Hard Goodbye
Even Evil Has Standards: Word of God is Kevin hates Roark Jr. and thinks he's an abomination. He briefly appears in the story and apparently ignores Hartigan as he goes to finish off Roark Jr. Any disgust from Kevin is not really apparent from the panels themselves, however.
The Voiceless: It is mentioned that he had a beautiful voice but he only spoke to Cardinal Roark. We never see or hear him speak in either the comic or movie, even in his final moments. Considering that Roark clearly had a few screws loose, it's entirely possible that the beautiful voice was only in his head.
Wolverine Claws: Kevin's nails are sharpened in order to act as deadly claws.
Douglas Klump & Burt Shlubb AKA Fatman and Little Boy
The Stool Pigeon: More than happy to drop the dime on anyone to rise in the criminal hierarchy or for a quick buck.
Basin City Mob
Herr Wallenquist (aka Mob Boss Wallenquist)
Expy: Given his tendency to wear single-color suits (usually white), his immense size, and his baldness, it's possible that he's basically a German version of Daredevil villain Wilson Fisk, The Kingpin. It's notable that Frank Millar did some of his better known early work in comics on Daredevil.
Genre Savvy: It's possible that this is the reason he's such an effective mob boss. Ava Lord is an obvious Femme Fatale, and while her seemingly supernatural ability to attract and manipulate men works on seemingly everyone, he simply tells her right away that "her charms didn't interest him". Furthermore, after Wallace deals a heavy blow to his operations, he simply tells his lieutenants that it would be too costly to go after the obvious heroic protagonist One-Man Army.
The Ghost: In many stories, he is mentioned and you can even see his plans coming to fruition but he never pops in. In fact, he never comes face-to-face with any of the heroes in Sin City, luckily enough.
Gratuitous German: Averted. His English seems perfect. It's likely that he's been in the US for a long time.
It's Personal: Also averted. Even when Wallace screws him over and takes out one of his organizations, he refuses to take revenge since it isn't financially viable.
Karma Houdini: Implied to be averted. Wallace reduces his "human resources" operation to shambles, killing many of his best agents except the Colonel who's killed by Liboweitz. Also, in family values, Dwight and the girls of Old Town frame his organisation for killing the Magliozzi mob family, which Dwight says will provoke a mob war between the crime syndicates.
Large and in Charge: He's very physically imposing and the most powerful gangster in the series.
Money Tropes: Hard to say just how many of these he fits, but he's a chilling villain who puts the "organized" in Sin City's organized crime, without ever even being threatened by any of the heroes, and he doesn't care about anything but making a profit.
Nazi Hunter: If the fan theory about him is true. See WMG for more details.
Dirty Coward: Despite her dream job being to kill people, when she's held at gunpoint by Wallace she begs him not to kill her. Doesn't work.
The Dragon: Seems to serve as this to the Colonel.
In Love with the Mark: Inverted. Her initiation to become an assassin involves killing the only man she's ever loved. She does so willingly. Afterwards, if she likes a target she tends to seduce them before killing them.
Card-Carrying Villain: She openly brags about being pure evil, saying that society throws around the word madness in an attempt to justify evil people's actions rather than admitting evil people do exist.
Non-Action Big Bad: Despite being the main villain in A Dame to Kill For, she mostly manipulates other people to do the dirty work for her. The closest she gets to being a physical threat in her own right is when she shoots Dwight right after revealing her duplicity.
Badass: Not only is he one of the few badguys that lives through more than one story, but he is the only one to survive confrontations with Miho, Marv, and Wallace. In fact, surviving a confrontation with just one of these people is badass enough, to say nothing of all three of them.