The Heavy is the villain whose actions drive the plot. One of the things that an average viewer has seen a million times.
This is a dominant role for an actor, frequently the largest role in a play or movie. The term, which goes back to theater in the 1800s, may refer to this player having the heaviest script.
This can be the Big Bad, but is more often The Dragon, since keeping the Big Bad mysterious generally makes him scarier. This is especially true in the case of a Non-Action Big Bad. In the original Star Wars trilogy, Emperor Palpatine may be the Big Bad, but Darth Vader is The Heavy. He's seen more. He has more to do. He dominates the films, and as the prequels prove, the story is about him.
Actors often cast in such parts are known for "playing the heavy."
Compare Dragon-in-Chief, which is when The Dragon fills this role specifically because he overshadows the Big Bad as a threat. Not to be confused with The Big Guy, the Heavyworlder, or the Gravity Master. Likely to intersect with The Villain Makes the Plot. Has nothing to do with the Heavy from Team Fortress 2 or the English band, The Heavy.
Zouken Matou in Fate/stay night. While Kotomine is the Big Bad, he always sends others to do his work and runs out of those quickly in Heavens Feel. Kotomine isn't even seen as an enemy until the very end, and its possible that no one even remembers that he was since Shirou is the only one who was there and his memory of the events is a little hazy, for good reason.
Hattori in Nabari No Ou appears to drive most of the plot, though he isn't actually theBig Bad — Fuuma is.
Naruto had Orochimaru, Pain, and finally, Madara/Tobi.
Eyeshield 21: Reiji Marco is The Heavy during the Kantou Regionals, with his obsessions and schemes driving most of the plot, and helping to totally upset the way the tournament was supposed to go. During the Youth World Cup, the Big Bad Duumvirate of Clifford D. Louis and Mr. Don take over as the main threat to the Devil-Bats, with their seeming invincibility driving the story for the remainder of the arc.
Mobile Suit Gundam splits this role between Gihren Zabi (whose actions drive the overall plot) and Char Aznable (who drives the plot of numerous individual episodes).
Mobile Suit Zeta Gundam has Dark Messiah Paptimus Scirocco, who manipulates everyone in order to become ruler of the world (we think). He seizes this role from Jamitov Hymen, the series' original Big Bad.
Mobile Suit Gundam SEED Destiny has Gilbert Durandal; he's not the only contender for the title of Big Bad, but he's definitely the shaping the overall storyline.
Comicbooks
Inverted in Sin City in which the heroic roles drive the plot. In Hartigan and Marv's stories, the main characters respond to crimes that happen off-screen to people they have little connection to. Because they decide to act, this leads them to make more decisions and the plot follows them. Dwight is an even greater example. He starts off reacting to Jackie Boy being the Heavy but he takes over the plot when he decides to chase Jackie Boy into Old Town and from there, his actions led to trouble from different directions. The main villain of that particular story doesn't have a part in the plot until the mid-way point.
Die Hard is something of a subversion. While HansGruber does set the events of the movie into motion, forcing other characters into action, and otherwise driving the entire plot of the movie, John McClane also sends the plot into other directions by being proactive and antagonizing Gruber. Their battle of wits, both men acting and reacting to the other, sets the general cat-and-mouse tone of the movie, with both taking turns in either role.
In most variations of Robin Hood, the Sheriff of Nottingham is The Heavy to Prince John's Big Bad.
Sauron is the Big Bad of Lord of the Rings, but Saruman (and to an extent the Witch-King and the other Ringwraiths) are much more visible and involved villains, especially in the movies.
The One Ring itself is more active and visible than Sauron. Sauron doesn't even really appear himself, ever. Gollum is more of an actual presence than the Big Bad!
Though Lord Voldemort is the Big Bad of Harry Potter, he's only The Heavy in the last book/movie, Harry Potter and the Deathly Hallows, which is the only time he has a substantial plot-spanning role. The role of The Heavy is therefore often taken by another villain, who may or may not be working for him—notably Lucius Malfoy in Chamber of Secrets and Dolores Umbridge in Order of the Phoenix.
The Full List is: Professor Quirrel in "Philosopher's Stone", Tom Riddle in "Chamber of Secrets", Sirius Black/ Peter Pettigrew in "Prisoner Of Azkaban", Barty Crouch Jr. in "Goblet of Fire", Umbridge and Lucius Malfoy again in "Order of the Phoenix", and Draco Malfoy in "Halfblood Prince".
Dead Beat: Grevane, who appears first and most often of the three necromancers and is fought most consistently through the novel, though he's probably the least dangerous.
Proven Guilty: The Scarecrow
White Night: Vittorio Malvora
Turn Coat: Shagnasty the Skinwalker
Changers: Duchess Arianna
For the series as the whole, the Red Court of Vampires are the most obvious and heavily featured recurring villains, though the Black Council is shaping up as series-wide Big Bad. With the Reds out of the picture, the Fomor look to be stepping into their vacated role.
Nom Anor in the New Jedi Order series. He's not the leader or even a leader of the Yuuzhan Vong, being a mind-ranked but influential intelligence agent, but he's by far the most recurring villain in the novels, and by the last quarter or so the series is as much about him as it is about the heroes.
Hawkfrost in the second Warrior Cats arc, The New Prophecy. While his dad Tigerstar is the Big Bad, Hawkfrost's schemes to take over the Clans are the main driving point, partially because his dad is dead and only appears as a Spirit Advisor.
AntonChigurh of No Country for Old Men, the most menacing and visible of those searching for the drug money. In theory there is a Big Bad Ensemble of the major players who hired Chigurh and the various Mexicans (implied to be the "Matacumbe Petroleum Group" and real-life drug lord Pablo Acosta), but they're ultimately rendered irrelevant by Chigurh's inscrutable, single-minded rampage, a point driven home when Chigurh kills the guy who apparently hired both him and Carson Wells for interfering with his work, then negotiates a new contract with the man at the very top.
Krait, the assassin in Dean Koontz'sThe Good Guy. He spends most of the book as the sole enemy hunting down Linda on behalf of a vaguely defined shadow government that is both explained and destroyed near the end of the book. Played with, as Tim also helps drive the plot by intervening in the hit, similar to the Die Hard example above.
Live-Action TV
Ben on Lost, especially in late season 2 (even without knowing his real name...) and all of season 3.
Diana in V. Jane Badler even got top billing, thanks to alphabetical order.
Anna in the new V (and though unlike Diana, she has no direct superior, there are other leaders whose combined might even she wouldn't want brought to bear against her.)
Sylar from Heroes, especially in the first season and the second half of Volume 4.
Smallville: LionelLuthor fulfilled the role in Seasons 1-3 (especially 3), Brainiac in Season 5, Lex Luthor in Seasons 6 & 7, and Major Zod in Season 9. Each was also The Big Bad of the season in question. The others are a lot more ambiguous about it, with multiple villains, numerous Big Bad Ensembles, and a lack of plot direction.
One could make a definite case for Earth-2 Lionel Luthor in the latter half of Season 10. Darkseid and his Co Dragons may be the Big Bad, but it's Earth-2 Lionel's schemes who drive most of the plots, and (unintentionally) enable Darkseid to eventually cross over.
Gatehouse of The Shadow Line. He's a Dragon-in-Chief rather than a Big Bad, but his plans are eventually revealed to be driving almost every aspect of the series's plot, even in the storylines he's apparently uninvolved with.
Theater
This type of villain was one of Shakespeare's specialties, three of the most notable being Iago in Othello and the eponymous characters of Richard III and Macbeth.
Golbez in Final Fantasy IV, possibly the most competent villain in Final Fantasy history, leads the heroes through an absolutely massive Xanatos Roulette involving almost the entire game before his Heel Face Turn. Oh, and he never loses a fight to the heroes. Come to think of it, no Final Fantasy games after III actually averts this trope.
A good example in Final Fantasy of a Heavy who is not the Big Bad is Seymour of Final Fantasy X. The realBig Bad, Sin, is actually a creation of long-dead summoner Yu Yevon, who is, according to a few people in the game, by now barely intelligent, neither good nor evil. Hence, while a dumb brute is scary (lordy, is Sin scary), he's not really compelling villain material. Enter Seymour, with the most lines and screen presence of all the antagonistic cast, engaged in a plan whose effects drive a great deal of the story.
Resident Evil 1: AlbertWesker. He may be taking orders from Spencer, but as Umbrella's man on the spot, it's Wesker who drives the plot, from luring the heroes in, to unleashing the Tyrant on them in the finale.
Resident Evil 2: WilliamBirkin. There are other villains, like the UBCS and Mr. X present, but Birkin is the most recurring threat, pursuing you from the earliest chapters of the game until your final escape at the end. Not to mention that the outbreak is his fault in the first place.
Resident Evil 3: Nemesis. Again, Spencer is The Man Behind the Man, and the USS and T-103's have their own agendas, but it's Nemesis who provides all the dramatic tension, chasing Jill and Carlos from one end of the city to the other in fullfillment of its mission.
Resident Evil 5: AlbertWesker again. With Sergei and Spencer gone, Wesker steps up as The Big Badand the game's most visible and potent physical threat, using everyone as part of his plan to unleash the apocalypse.
In FEAR, Alma. Pretty much everything that happens in the game is a direct result of Alma's actions, whether they be conscious or unconscious. What isn't a result of her actions are due to Genevieve Aristide, Harlan Wade, and Paxton Fettel, but none of them have as much presence in the games.
The same could be said for Chancellor Cole. Like Ghirahim, everything he does is in the name of resurrecting his master, but he has a much greater presence in the plot compared to Malladus himself.
Emeraude in Tales Of Graces is probably the most notable example. At no point in the game is she positioned as a main antagonist, but flashbacks reveal that she is the root cause of everything that goes wrong in the story.
Saren in Mass Effect 1, Kai Leng in Mass Effect 3. The former remains Shepard's most personal enemy even after it's revealed he's the servant of a much bigger threat. Kai Leng, by contrast, is the guy the Illusive Man (an exclusively mental opponent) sends to get his hands dirty. As a result, Shepard doesn't bother trying to teach Leng the error of his ways and just shanks him.
Mystique in the first season of X-Men: Evolution. She runs the Brotherhood, and Magneto, usually only seen in shadow, runs her. Eventually, Magneto takes over the role himself, and later Apocalypse.
This is actually subverted in Season 3, where Azula, Zuko, and the Gaang each act independently and proactively in order to drive the plot.
Zhao arguably held the role in Season 1.
Slade, whenever he shows up in Teen Titans - even when serving under Trigon the Terrible (see Vader and Palpatine - while not the Big Bad, Slade is a menace through the season, while Trigon is a threat only in three episodes.)
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