Kingpin in His Gym

"I gotta work out so I can kill the world!"

—Harry Russo, Schizophreniac: The Whore Mangler

Some Almighty Overlords like to do more than lounge around on nice chairs in their fortresses. They'll go for a bit of self-improvement instead. Some may get a Training Montage or two, while others may pursue a Dangerous Forbidden Technique or Forgotten Superweapon in parallel with The Hero. Regardless of how they choose to better themselves, showing a villain building his prowess can be a menacing taste of what's to come when the heroes finally reaches his doorstep. Like our good old friend, however, they don't pose any direct physical threat to the good guys at the moment.

One of the ways to show that a villain's Authority Equals Asskicking. However, if the training sessions are shown to be a walk in the park, one wonders how they will make the villain any stronger. Shopping is another popular hobby of villains.

Contrast with Orcus on His Throne and Slouch of Villainy.

Examples of Kingpin in His Gym include:

Anime and Manga

Geese Howard hadn't been the Big Bad since the first Fatal Fury OVA, but in the third, Billy Kane finds him training in the woods. After receiving the report on the heroes' activities, Geese busts out a Raging Storm that obliterates some of the surrounding vegetation.
Hayate × Blade also shows Ensuu doing crunches hanging off the top half of a bunk bed and jogging in the school gym on two separate occasions before facing off with the protagonists' team.
In Death Note Teru Mikami, Light's right-hand man, visits the gym religiously. Given that his method of killing just involves writing down names, this is purely for his own benefit, and has nothing to do with fighting.
- Then again, considering how animated he is about writing down names, he possibly does it to avoid pulling something.
While not exactly a villain, the Raikage in Naruto is introduced lifting huge dumbbells in his gym. Oddly enough, he's the only leader of any group that's been seen training at all so far, despite the setting being a World of Badass supernatural ninjas.
Tao Ren is shown working out in the lead-up to his first official tournament fight with the protagonist, who doesn't exactly share his obsessive work ethic. Of course, since Ren is a walking ball of issues and Shaman King the rare shonen series where Unstoppable Rage does not help, Yoh's mellower approach works in his favour.
General Silver from Dragon Ball is shown working out at least once in order to beat Goku. It doesn't work.

Comic Books

While his flunkies were making life a nightmare for Spider-Man, The Kingpin was shown performing some outrageous physical feats like bending steel bars and breaking large objects in preparation for his personal disassembling of Spidey. He is therefore the Trope Namer. A running joke with Kingpin is that he'll pay goons (more often than not, having martial arts training) to attack him for practice. If they lose badly to Kingpin, he'll fire them - but if they put up an actual fight, then Kingpin murders them for making him look bad. He also tends to kill one of his practice partners in every match, so that the survivors will fight harder next time.
Fellow Marvel Comics villain The Mandarin beat six top martial artists during a training exercise.
Subverted by Lex Luthor. Shortly after coming back as his own Evil Clone (don't ask), he is shown training in martial arts in his gym. After his trainer hands him his ass in front of witnesses, he later tracks her down and murders her in cold blood.
- Inverted in his last days as President, when he is using Venom (a kind of super-steroid) to muscle up.
Eddie Brock's first appearance established him as a gym bunny, who channeled his rage against Spider-Man (prior to actually becoming Venom) via working out.
Issue 350 of Captain America showed the recently-resurrected Red Skull practicing his hand-to-hand skills by slaughtering several of the Taskmaster's trained cronies... all of whom were dressed as Captain America.
- Later stories expanded upon this: Red Skull never tells his would-be appointments that he is going to fight them to the death, just for the added lulz of watching them panic when they realize that Skull was going to kill them.

Film

Rocky Balboa's major opponents got their own Training Montages, which often told viewers something about their character: Clubber Lang's dungeon-like basement emphasized his monstrosity while Ivan Drago's almost clinical routines (and his steroid use) showed his lack of "heart."
A few Bond villains are fond of this:
- Largo practices his aim with clay shooting in between stages of SPECTRE's plan to detonate stolen nuclear weapons in Thunderball.
- Scaramanga, The Man with the Golden Gun, has a warped relationship with his diminuative manservant Nick-Nack; in the event of his death, Nick-Nack inherits everything...in return for Nick-Nack actually trying to kill him by hiring the best assassins in the world for Scaramanga to pit his skills against.
- Max Zorin sparred with his Dragon May Day in A View to a Kill.
- Colonel Moon in Die Another Day, whom we meet taking his Tae Kwon Do- frustrations out on a punching bag containing his anger therapist- that'll teach him to lecture Moon. Big Bad Gustav Graves also has some fun at a fencing club. We later find that they're the same person.
In the Jet Li film Fist of Legend, the Big Bad General Fujita gets a scene showing him training by hammering nails into boards with his bare palms, smashing slabs of rock, and letting a team of students break thick wooden rods over his body, to establish his overwhelming power and resilience in combat.
In Gladiator, Commodus practices his swordsmanship against multiple opponents, showing that wealth and power have not made him soft.
In Dragon Tiger Gate the Big Bad is introduced and almost exclusively shown in his personal training area... including the climactic battle.
The 2011 film adaption of The Three Musketeers 2011 shows Richlieu sparring in his off-hours. With three opponents, no less.
Count Dooku, a.k.a. Darth Tyranus, was shown sparring with General Grievous in the Star Wars: Clone Wars animated series. Most other master vs. apprentice fights in the Star Wars universe tend to be cases of attempted Klingon Promotion although they could be considered training for the apprentices.
- Prince Xizor inverts this in Shadows of the Empire: He has an "exercise chair" which stimulates his muscles while he lounges around in his fortress, giving his exercise without him having to lift a finger. He has constant problems with the chair's voice-chip pronouncing his name, though. Darth Vader is also seen training against lightsaber-wielding battle-droids, which helps to characterize his frustration with his inability to fight an opponent with the power of the Force.
  - Xizor is, however, a genuine and efficient martial artist, single-handidly disarming and killing an assassin with little difficulty. So he does play this trope straight, offpage anyway.
  - In fact, the reason he uses the myostim unit chair is because he's at the peak of what exercise alone could do for him.
  - He uses the chair because excercise bores him. He prefers eating at his expensive restaurant, date-raping and dumping mind controlled babes, and musing how much better he was than everone else. He's closer to an Orcus on His Throne, were it not for the fact that spends a lot of time engaged in various evil schemes.
- In the X Wing Series comics, Ysanne Isard is once shown training against Mrlssti laser phantoms while she works on her plots to control the Empire. In one novel she talks to an Enemy Mine while using a weight machine with no sign of strain. Notably, Isard never actually fights people herself, preferring schemes and Manchurian Agents. Apparently she believes the old adage about healthy body, healthy mind.
The main villain in the second Transporter movie is practicing Kendo against multiple opponents in his introductory scene.
Robin and Marian establishes the Sheriff as a credible threat by having him practice swordsmanship against three men at once. When he and Robin do fight... well, they're Robert Shaw and Sean Connery.
Memnon in The Scorpion King.
In Snakes on a Plane, crime boss Eddie Kim is shown practicing karate while ordering the titular plan. Could have been a Chekhov's Gun for an eventual Kung Fu faceoff with Samuel L. Jackson, but nope.
In Kick Ass, Frank D'Amico is shown training in the gym to show he's a step above his mooks, later on even using his skills against a hapless superhero cosplayer. His son is shown clumsily messing around with some weapons.
In V for Vendetta, there's one scene in which V has some fun fencing with a suit of armour. As he exists somewhere in the fuzzy border between Anti-Hero and Anti-Villain, he's probably villain enough to count.
From Avatar we have Col. Quaritch lifting weights, who comments on the fact he needs to keep his muscles in top condition in Pandora's low gravity.

Literature

Prince Humperdinck in The Princess Bride, with his Zoo of Death.
Feyd-Rautha Harkonnen participates in gladiatorial matches, trading traditional means of rigging the fights with his own, to make it look like he's in danger and earn prestige. This almost backfires when the slave in question nearly kills him. Feyd, impressed with and knowing how to play to the crowd, doesn't do the traditional mutilation of the body, instead allowing him to be buried intact, as a sign of respect.
Benito Ramirez of the Stephanie Plum books actually does train in a gym, being a boxer. He uses it to great effect to terrorize women.

Live-Action TV

In Season One of The Wire, Big Bad Duumvirate Avon Barksdale and Russell "Stringer" Bell were shown working in the gym and on the basketball court while planning gangland operations.
Played for laughs in Doctor Who when the Delgado Master, locked up in a sea fortress, exercises on a rowing machine. It doesn't seem to be working, though—the Doctor remarks that the Master has put on weight!
Stargate Atlantis: When we are first introduced to him, Commander Kolya of the Genii is having a sparring session with some of his military subordinates.
Various episodes of The Wild Wild West had scenes of the episode's Big Bad either sparring or actually fighting with one or more of his underlings. Unless said Big Bad was Doctor Loveless, these episodes invariably had said Big Bad later dying in the same room, as a result of making a fatal mistake while fighting Jim West.

Web Comics

Though not shown on-panel, dialogue states that The Order of the Stick's villain, Xykon, spent the entire duration of Roy's absence researching new spells and crafting magic items, the Evil Sorcerer's equivalent of working out.
- Of course, the nature of reality there renders him incapable of doing this for longer than 8 hours per day, and, as a lich, he doesn't sleep, either. As such, he generally spends the rest of his day messing around in a bid to alleviate his boredom, which is what the reader usually sees whenever Xykon is present.

Western Animation

Spoofed in The Simpsons, where Mr. Burns makes Smithers work out on his behalf.
In Gargoyles, David Xanatos enjoys sparring in a dojo. As always subverting such things, he shows how Badass he is by losing to his Battle Butler and then commenting on how surprised he was that Owen has improved.

Owen: Would you prefer I pretend to lose, sir?
Xanatos: I'd fire you if you did.

Not totally subverted, though; the rest of the episode, which seems to be a pointless attack on the Gargoyles, is revealed to be Xanatos convincing himself that he hasn't lost his "edge". Not that losing was detrimental to his plan.

Both Prince Zuko and Princess Azula each spend one of their respective first appearances in Avatar: The Last Airbender practicing their firebending. Zuko demands to learn the advanced techniques even though Iroh insists he hasn't mastered the basics yet. Azula, on the other hand, does the advanced bits flawlessly—but completely freaks out (foreshadowing her ultimate Villainous Breakdown) when one hair falls out of place.
Done three times in the second Teenage Mutant Ninja Turtles 2003 series. The first occurs with the Shredder, who gets a training scene in the episode "Darkness at the Edge of Town". The second occurs with Karai, whose very first scene is of her training. The third time occurs in a supplementary short of dubious canonicity, also featuring Karai, which shows her apparently killing the four turtles...until its revealed that they're actually advanced training robots.
Tombstone does this in The Spectacular Spider-Man. Fitting, since that adaptation promoted him to the Kingpin's usual role; they couldn't use the Trope Namer himself due to copyright issues.
One chapter of Star Wars: Clone Wars opens with Count Dooku sparring with General Grievous.
In one episode of Batman: The Animated Series, mobster Rupert Thorne is in his private gym, punching a bag while a henchman — named Dicky — holds it for him and urges him on. Thorne is clearly getting a little tired, but then Dicky says, "Come on, boss! No wonder the Batman is runnin' circles around ya!" Thorne snarls and punches Dicky in the face, knocking him out. Then he grabs a towel from another thug, mentioning before he leaves, "Oh, and when Dicky gets up, tell him he's fired."