"Ya got trouble Right here in River City! With a capital 'T' And that rhymes with 'P' And that stands for Pool!'" —"Ya Got Trouble", The Music Man
Billiards. Doesn't seem like a particularly evil game, right? Despite accusations that the cueball is "possessed," "cursed," or "hates me personally," pool typically isn't what comes to mind when you say "things a bad guy would enjoy." In fact, its image has softened by now to be considered a respectable game of skill for any age, and even used in kid's Edutainment shows like Beakman's World to illustrate rebound trajectories.
Unless, of course, you're in the movies, where if you see someone playing pool, there's a 90% chance they're planning some dastardly deed at the same time. Whether it's due to negative connotations regarding the term "pool shark", or possibly due to the fact that pool is associated with illegal betting rings (which also serve as a convenient motive for a cash-starved antagonist to do any feats of nastiness the story requires), the image of a group of Big Bads and thuggish Mooks shooting eight-ball seems to be engraved in the minds of filmmakers. The Anti-Hero and others may also play pool, to emphasize how cool, dangerous, and outside the norm they are.
For the Femme Fatale and The Vamp, it's also a free excuse to get them to bend and sway in a variety of manners, showing off their body and especially their legs, and it gives them three ways to end the scene: Keep on flirting and end on sexy; Humiliate the mooks by beating them at their own game; or just start a Bar Brawl.
Part of the origin of this trope is in pool halls having been The New Rock & Roll once upon a time, like bowling before them and video arcades afterwards. Its continuing popularity now is likely due to a pool table's ability to fit nicely inside a Bad-Guy Bar or a family-friendly Den of Iniquity. If a Fight Scene ensues, as it inevitably will, expect the cues to be used as clubs, swords, or broken in half and used to stab people, not to mention the balls themselves are really effective to throw at people.
One of the players in Princess Nine is recruited at a pool-hall. Yes, she's the delinquent of the group.
In Black Butler, there is a scene of people playing pool. The protagonist (Who is sort of an Anti-Hero at that point, though a full-on Villain Protagonist later in the series) is among them, as well as the bad-guy for that chapter. There's also a metaphor involving getting rid of evil, being evil, and some other things involving the pool table.
Code Geass: a bunch of antagonist-ish characters play pool right after nuking Tokyo. Something of a subversion as all of them were rather put off by the guy who actually did it (who incidentally wasn't playing).
This, however, wasn't so much because of the act being carried out, but rather his sudden change in behavior, when he volunteered to assassinate The Emperor.
Although the Sinners of Chrono Crusade are never shown playing pool, they definitely at least have a knowledge of the game—when Viede chases after Aion during a battle to give him his sword, they have this exchange:
Aion: What did you come here for? To ruin my game?
Viede: You can't play pool without a cue stick, Aion.
The Amazoness Quartet from Sailor Moon aren't shown playing pool for fun, but their main method of retrieving someone's Dream Mirror involves shooting a ball at the victim with a pool cue.
In Weiß Kreuz, when Omi has a nightmare about being a murderer just like his older brothers, he imagines the three of them playing pool.
The villainous 8-Ball, the first supervillain battled by Sleepwalker, took this trope to its logical conclusion when he not only proved to be a master pool player, but went so far as to base his whole criminal schtick on the game.
Bullseye can be seen playing pool from time to time. Since he has nearly superhuman aim, he's quite good.
Also inverted as heroes who also possess superhuman aim (Hawkeye, Cyclops, etc) are also frequently seen playing pool in their spare time.
Not a villain, but Heath Ledger's character in 10 Things I Hate About You hangs out in a bar playing pool to emphasize his mysteriousness and show how outside the norm he is compared to the other students.
Superman Returns, although this is slightly played with since the pool table is on Lex Luthor's yacht.
In That Was Then, This Is Now, there's no fight scene in the bar/pool hall itself, but the protagonist and his friend end up getting mugged by a couple of thugs outside, after winning a considerable amount of money off of them playing pool. The bartender shows up, shotgun in hand, to drive the goons off, and the boys walk away unharmed. The bartender himself, however, gets a bullet in the head for his troubles.
The pool hall where Jackie Chan makes his famously ill-advised attempt to learn Afro-American slang in Rush Hour is a pretty rough place, if not actually criminal (in most cases).
Taking a cue from Pinocchio, below, the headquarters for the Foot Clan in the Teenage Mutant Ninja Turtles live action movie has a huge game room filled with typical '80s/'90s delinquent kid activities to keep their underage Unwitting PawnsNinjaMooks pacified, including a series of pool tables.
They never get around to actually playing in the movie, but the young ladies who play hostess to The Warriors have a pool table in their hangout. And a Bar Brawl does break out, including a fine display of shooting.
Inspector Clouseau does this with Benjamin Ballon (the "bad guy" in this case) in A Shot in the Dark, interrogating Ballon, innocent at the time but eventually one of the four murderers in the case he is on, in the process.
In Boondock Saints, when ambushing a mafia hitman at his house, said hitman and his friends were playing billiards. Rocko even kills the hitman with the cue ball.
In Horatio Alger, Jr.'s The Erie Train Boy, the hero Fred is sent into a seedy bar in Canada where he plays pool with a robber to endear himself to him and get access to his stolen loot.
Gwendolyn Brooks' poem "We Real Cool", subtitled "The Pool Players: 7 at the Golden Shovel".
We real cool. We
Left school. We
Lurk late. We
Strike straight. We
Sing sin. We
Thin gin. We
Jazz June. We
Brooks—during a reading at the Guggenheim—said the poem has been "...banned here and there because of the word 'Jazz'," the line frequently having been interpreted as a euphemism for sex. Not intentional, she averred: but also remarked, "I have no objection if it helps anybody."
In Donna Tartt's The Little Friend, Harriet, believing a local boy is responsible for the death of her brother, sends her friend to spy on him in the pool hall.
One episode of Firefly starts with the discussion of slave-trading over a game of holographic billiards.
Mal even tells Inara to get out, since there's a thief about. Mal Reynolds, of course. Once the slaver victim finds out, cue Bar Brawl. Note that as far as Mal's concerned, his presence is playing the trope straight.
In Boy Meets World, Frankie "The Enforcer" is a noted pool champion at Chubbies. Subverted in that so is Eric.
The Aryan Brotherhood from "Oz" (at least, the members residing in Unit B) will often be seen playing pool during their scenes.
Arnold Rothstein in Boardwalk Empire is depicted playing pool in about half of his appearances on the show.
Beyond simply playing the game, Rothstein also tells a particularly chilling anecdote about a man and a billiard ball trick...
Kilo, a gangster in the Season One episode "Confidence Man" of LOST, threatens Sawyer who borrowed money from him while playing pool.
An episode of Law & Order played with this trope. Lenny Briscoe posed as a guy asking for a hit while playing pool with a Mafioso. The Mafia guy was dumbfounded that the guy who could play pool that well was a cop.
The Sopranos crew are often found shooting pool in the Bing's back room.
Comically subverted on Gossip Girl where Chuck Bass owns a pool table, but the only person who ever uses it is his goody-two-shoes best friend Nate.
In Smallville, Lex Luthor is either doing this, playing the piano or drinking whiskey. If he does all three within the space of a single episode then he's being particularly evil.
On the pilot of Leverage, Nate and Eliot play pool while discussing being the bad guys for a change.
The Get Smart episode, "The Dead Spy Scrawls," had Smart learning to play pool to get close to a KAOS agent in his pool hall. Unfortunately, Smart is so hopelessly clumsy at the game that 99 has to use a special remote control cue ball to help him play.
The BBC sports show Pot Black was a deliberate aversion of this trope, with the intent of restoring respectability to the game of pool as a professional televised sport.
In the classic Hawaii Five-O, a few Mooks are scrambling to cover up when they hear Five-O coming. Before our heroes leave, Danno quips, "One of you sank the cue ball."
The 1980's hit Shaddap You Face by Joe Dolce features the line: "Mama used to say don't stay out-a late with the bad-a boys, always shoot-a pool, Giuseppe going to flunk-a school."
The video for Michael Jackson's "Smooth Criminal" has a bunch of gangsters paying pool in the back of the bar, before being interrupted by Jackson snatching up the cue ball and crushing it in his bare hand. The players are understandably annoyed.
Shooting pool is among the unproper things Eartha Kitt sings about wanting to do in "I Want To Be Evil."
The music video for "Bad to the Bone" by George Thorogood and the Destroyers has George in a pool match against Bo Diddley.
The video for AC/DC's "Sink The Pink" deals with a hot female pool shark named Suzy Cue.
I Love Bees has antagonist Thin play Action Girl protagonist Jan for a man's life. As it's set in the future, the game is called moons, but it's basically pool with pinball sound effects.
When the CHIKARA tag team 2.0 went under the Paper-Thin Disguise of the Badd Boyz, they cut a promo proclaiming their toughness in the most stereotypical way possible. Of course, they were shooting pool the entire time.
In The Music Man, Harold Hill gets River City riled up over the idea that pool, just recently introduced to the town, will corrupt their children. He makes excuses for billiards, which River City already has, saying that it's the pockets in a pool table "that mark the difference between a gentleman and a bum."
In the Looney Tunes short "The Dover Boys", a spoof of turn of the 20th Century "Mellerdramas", bad guy Dan Backslide "that coward, bully, cad and thief of Roquefort Hall" is first seen playing pool in "a tavern of unsavory repute" so vile that the Boys and their lady love have to avert their eyes as they bicycle past.
The Spectacular Spider-Man has a pool hall that, other than the bar, is quite literally nothing but at least a dozen pool tables. Some rather unsavory characters hang out here. Gamblers frequently are seen here, too, as Blacky Gackston works from this hall.
It's explicitly noted that the bar belongs to Montana, leader of one of the show's two Quirky Miniboss Squads. His superior, Tombstone also has a pool table in his office, and is seen playing. Green Goblin also plays pool, getting every ball in the pocket but one, and he blows up the one remaining.
There's a pool table in the Bad-Guy Bar for Flash villains in Justice League Unlimited. The players flee when Batman enters the bar and it's later melted by a deflected shot from Trickster's snot gun.
An episode of Gargoyles had Elisa playing pool with some gangsters in an attempt to convince them she had gone crooked.
Our first (and, for all intents and purposes, last) look at the Ts' lair in Batman Beyond is of their leader playing some kind of futuristic pool that involves the ball exploding when it lands in the corner pocket. Then Batman drops in, at which point Fat T promptly attacks him with the cue. It doesn't take.
There's also a pool table in the villain's club in Batman: The Brave and the Bold, surrounded by very colourful and very silly villains. Someone in the DC animation team must like this trope.
Back in the early 1990s, when London's Slimelight was a Hell's Angels hangout, they could usually be found playing pool on the top floor. When there were drug dealers about, they would also pick that spot. These days, the pool tables are situated on the ground and first floor seating areas and not the exclusive domains of "bad guys".