24: Tony Almeida fits almost every part of this description in relation to Jack Bauer. This is an interesting case in that Tony initially seems like a calmer, saner, more soft-spoken counterpart to Rabid Cop Jack. But placed under enough strain (as exemplified by how they each handle the loss and/or potential loss of their wives), Tony can actually be far more emotional, reckless, self-destructive and vengeful than Jack.
Agents of S.H.I.E.L.D.: Melinda May. She's recruited to be Phil Coulson's second-in-command, and her Ice Queen demeanor contrasts with Coulson's friendlier one.
Several characters have Lancer qualities. Doyle was the initial one, but for most of the series, Wesley fulfilled this role as well as The Smart Guy. Gunn also filled this role for a time late Season 3 and early Season 4, but was usually The Big Guy. Connor fit for much of Season 4. Easily the best fit that doesn't overlap with any other roles is Spike in Season 5.
Wesley, true to the trope, was the ruthless member of the team, as well as the sorcerer of the bunch, also betrayed the gang to save Connor, stabbed Gunn and shot Knox during his Roaring Rampage of Revenge, and, being the less stable of the group due to Fred's death, was expected by Cyvus Vail to make a move for Angel's position. Aware of it, Wesley pretended to be planning to betray Angel in order to get close to Vail and kill him. As the trope goes, Wesley was killed by Vail instead.
Cordelia was Interim Lancer between Doyle's death and Wesley's integration into the main cast, and was always Angel's real foil, despite being The Heart throughout.
Arrow: John Diggle to Oliver Queen, being the latter's very first ally and eventually his Number Two once they formed a large team.
Garibaldi is more aggressive than Captain Sheridan, prone to independent action, more of a covert operative, and does indeed get brainwashed at one point.
Ivanova is the pessimistic — sorry, make that Realisticdry-witted executive officer. She's remarkably tenacious, hammy when angered, and a spy master on par with Garibaldi at his best. Her fiery personality particularly contrasts with the original commander, Sinclair.
Blake's 7: Avon, even when Blake vanishes/dies and Avon slowly goes Ax-Crazy. Avon is very unusual — a Lancer as leader as nightmare.
Buffy the Vampire Slayer: Willow and Faith can act Lancer-y. Oh, and also Xander, despite also being the Butt-Monkey. In addition, Cordelia was this in the earlier seasons and when she left to be on the show Angel was replaced by Spike.
Chouseishin Gransazer: The Wind Tribe are essentially a trio of Lancers, and all of them fill this role in some way to Tenma and the Flame Tribe. Akira is the calm and pragmatic one, Ryouko is the Cool Big Sis and Jin is the laidback and free-spirited one.
Genseishin Justiriser has Yuka Sanada / Riser Kageri, the more mindful foil to Shouta / Riser Glen as well as his tsundere love interest.
Chuck: This tended to vary quite a bit depending on the season, and whether one is dealing with Team Bartowski or the Buy More, but:
Sarah usually filled this role for Chuck, as the series typically saw them collaborating together more often than not. That said, at times there were episodes where Casey filled the role instead.
Other times, Chuck himself took on the Lancer role to Sarah or Casey in episodes in which they were the lead of an episode.
Outside of the spy game, Morgan was Chuck's Lancer.
Once Morgan joined the team in the back half of Season 3, he was often the Lancer to Casey.
Morgan was also Big Mike's lancer once promoted to Assistant Manager. This then gets reversed when Beckman places Morgan as Store Manager, with Big Mike as his "Ass Man."
CSI: Miami: Ryan Wolfe has qualities of this. However, Eric Delko is a better example of the Lancer to Horatio's hero. Womanizer, leader, outgoing, and willing to take initiative on his own to further the team. Add to that he's completely loyal to Horatio.
Dad's Army: Sergeant Arthur Wilson, he's Captain Mainwaring's polar opposite, second in command and best friend/rival.
In the first serial, Ian prevented The Doctor from bashing a caveman's skull in. This has been one of the reasons The Doctor keeps companions, to keep his humanity in check and prevent him from slipping into darkness. So to an extent, they're all Lancers. Episodes like "The Waters of Mars" and "The Family of Blood" in which his companions couldn't control him, show this very well.
Captain Jack Harkness filled this role during his very short tenure.
Doctor Who usually has a small ensemble, but groups exceeding three members would occasionally contain Lancers; for example Rory Williams and Ian Chesterton, both more 'classical' heroes in contrast to the Anti-Heroic Doctor, and Tegan Jovanka, an unwilling passenger in the TARDIS who eventually left on her own accord. The thing about the Fifth Doctor adventures is that his companions hardly ever seemed to tolerate each other (Turlough, Tegan, Adric), apart from Nyssa.
Donna Noble, one of the most popular companions of the Tenth Doctor, shares a similar background and personality with Tegan.
Tegan retained her old personality in her early Big Finish appearances. This was a bit too much for her opening story. She always was a moaner but this was taken so far it was almost a parody; The Gathering suggests that traveling the TARDIS ruined her life and gave her brain cancer. She calms down a bit in Heroes of Sontar and Emerald Tiger and provides some of the more amusing moments in later trilogies. It's almost hard to reconcile this sunny, smiling TARDIS team with the same ones who glowered throughout "The King's Daemons"....
Joe Ford: Tegan is moaning because she doesn’t like the idea of Turlough traveling with them (and no its isn’t because she wants the Doctor all to herself, pipe down all you shippers at the back!) ...It's true that she is at least very honest, there is nothing that she would say behind Turlough’s back that she wouldn’t say to his face. More’s the pity: because now we have to listen to it twice. Then once all the bile is extracted from her gut she turns round and tells Turlough that he should stay! You know when hackneyed male figures in fiction stick their hands on their hips and cry ‘women!’ at something exasperating? I think that should be adopted here but the word changed to ‘Tegan!’
In Series 10, Nardole starts out seeming like he's nothing but a Sidekick, but as the season progresses, he develops into a sometimes-reluctant but always-capable former Hero of Another Story who has "authority to kick the Doctor's arse" if need be.
Bill: Nardole, are you secretly a badass?
Nardole: Nothin' secret about it, babydoll!
Probably the ultimate Doctor Who lancer is Brigadier Alistair Gordon Lethbridge-Stewart. In terms of the UNIT command structure, the Doctor is more his Lancer (or The Smart Guy), but in practice, both of them know it's the Doctor making the decisions and the Brigadier implementing them. He's as committed to the military way of doing things as the Doctor is opposed to it, which occasionally results in differences of approach, especially in the early days, but ultimately the result is a good partnership and friendship.
Farscape: Either D'Argo or Aeryn was the Lancer for Crichton, depending on the episode. Ironically, this also makes D'Argo Supporting Leader after being elected Captain of Moya.
Firefly: Zoe plays the cool-headed Lancer to the often impulsive Mal, and Jayne plays the Lancer.
The Flash (2014): Cisco Ramon to Barry Allen. Cisco is the one who usually accompany Barry in missions and is the second metahuman member of Team Flash after Barry himself.
Abe is this to Henry for most of his life. He brings a mortal perspective and a love of getting involved with other people, versus Henry's immortal POV and reluctance to risk getting hurt emotionally.
Within OCME Lucas plays this role to Henry. His youth, enthusiasm, and pop-culture-laden modernity contrast Henry's vast experience and general cluelessness about TV, movies, and graphic novels.
Hanson serves as Jo's lancer, her actual official partner who always has her back and puts up with Henry's antics for her sake.
Gobo, the reluctant leader of the Five-Man Band, had two extremely opposite Lancers — his best friend Wembley and Wembley's constant rival Red.
Although they get considerably less screen time, the Minstrels are a clear cut Five-Man Band, and it's obvious that Murray acts as the Lancer to Cantus.
Game of Thrones: Davos is the lancer to Stannis' Hero. Unless you consider Stannis a villain, then he's the Token Good Teammate. Following Stannis' death, he serves as this role to Jon Snow, being a great asset in recruiting forces to take back Winterfell and also being his second-in-command along with Tormund Giantsbane.
Giant Saver: It is a sentai show, but Thunder Guard Xu Weizhen takes the cake on the whole "rival and foil to The Leader" part of the trope. He is constantly a jerkass toward Dakong, the Fire Guard, and his cynical, money centered world view couldn't be a better contrast to Dakong's Wide-Eyed Idealism.
Happy Days: The Fonz fits the definition so well it's almost scary. What made the show a hit was the contrast between super-cool ladies' man and high school dropout Fonzie, and the gutsy, strait-laced, all-American Richie Cunningham. As shown in a flashback, the two didn't initially see eye-to-eye, with The Fonz being in a gang. However, he is impressed that Richie had the courage to stand up to him, and quit the gang he was in because of Richie's insistence that he was cool enough without a gang jacket to show for it; afterwards, the two became close friends and, when Richie left to pursue his dream of being a screenwriter, his final words were to Fonzie, who he dubbed a brother and a protector.
First is Archie Kennedy, a Composite Character given traits of several midshipmen (and ordinary seamen) who served with Horatio in the Midshipman stories. His role was greatly expanded because the cast and crew enjoyed Jamie Bamber's performance so much. Archie is much more cheerful and friendly than reserved, awkward Horatio, but he's also got worse luck and he doubts his abilities as an officer in the same measure that Horatio doubts his abilities at being a person. The Forester estate ordered the show to write the character out in the second series, feeling that his presence was altering Horatio too much.
Second is William Bush, Horatio's best friend from the novels. The dynamic is much different — Bush is a cautious, steady, and thoroughly reliable officer who does not tolerate indiscipline. Though not a genius or a Military Maverick like Horatio, Bush can face most troubles with a straight face and has very little in the way of self-doubt, which makes him an excellent Number Two. He's also much more perceptive than Horatio in certain areas.
Hotel Babylon: In this British series, the concierge Tony is a seasoned pro at the hotel business and very well-respected among his colleagues. When a general manager strays, he's usually one of the first to stand up for the good of the hotel or its staff and let a manager know he's going in the wrong direction.
House: Drs. Wilson and Foreman are both lancers to Dr House in different respects;
Wilson is House's best friend, his opposite in almost every way, and the one most likely to play the Only Sane Man. In fact, when Hugh Laurie first read for the part of House, he was under the impression that Wilson was The Hero, and that House was The Lancer.
Foreman is the subordinate most likely to oppose House on any given matter, and in later seasons has become the de factoNumber Two of the team (having stepped into the position of leadership on three separate occasions). Though his characterization has emphasized a fundamental similarity between himself and House, there are important (perhaps deliberate) differences — Foreman is stuffier than House, presenting an air of consummate professionalism in contrast to House's slip-shod and free-wheeling style of management.
House of Anubis- Patricia Williamson, being the Anti-Hero to Nina's Hero, and being the most independent member of Sibuna. She also fits this role in the third season Sibuna as well.
Inspector Lynley: DS Barbara Havers to the Inspector; she challenges him at every turn and is the first to tell him when she thinks he's being an idiot. She would also follow him into fire if he asked her to, and anyone who challenges him will find themselves on the wrong end of her fury.
Legends of Tomorrow: Since The Team is very large, three people have quickly vied for this role; Ray Palmer, Sara Lance and Leonard Snart. All three are the ones frequently questioning The Leader's decisions and all three rotate on being the acting leader in case the real one isn't present, though Ray, The Leader's very first recruit, is the one who is assigned for the role most. Once Mick Rory rejoins the team 3/4 into the first season, he also starts vying for the role.
Leverage: Sophie most cleanly fits this role, often serving as a foil to Nate in the planning process, though the rest of the crew also occasionally fits into it at times. Eliot in some ways fits this role, as the opposite of Nate, preferring to fight his way out of situations then Nate's Chessmaster style. Parker in some ways fits into this as the only true thief among them, as well as being a skilled planner when it comes to heists. Hardison also is trying to develop the skills to run his own crew as well.
Jack is unquestionably The Leader of the survivors throughout the first four seasons, but multiple characters alternate the role of his Lancer.
John Locke is Jack's ideological rival as the man of faith to Jack's man of science, but also frequently serves as Jack's Number Two when making important decisions about the fate of the group. When Jack is captured by the Others at the end of Season 2, Locke is the leader that the survivors turn to and he is the one who leads their rescue mission. When the freighter team arrive on the Island in Season 4, causing a rift between the survivors who believe that the freighter has come to rescue them and those that believe they need to prepare to fight them, Locke leads the latter faction in opposition to Jack leading the former. Though they butt heads throughout the series, it's clear that Locke has enormous respect for Jack as a leader and is frustrated that Jack rarely heeds his advice or returns that respect.
In Season 2, after the tail section survivors join the main group, Ana Lucia, The Leader of the Tailies, often plays the role of Jack's second in command. She contrasts Jack by being a much harsher and more authoritarian leader, but Jack's clearly values her input and is close to the only member of the camp who trusts her, even proposing that she train and lead an army of the survivors to fight the Others, although this idea is unfortunately rendered moot by Ana Lucia's death.
Though Sawyer often plays Commander Contrarian to Jack's decisions in the first two seasons, he becomes his Lancer in Season 3 after Locke leaves the survivors to join the Others. Sawyer clashes with Jack over whether or not to trust Juliet, but he is ultimately in his most supportive role to Jack in the entire show during this period. As always, Sawyer's rough Con Man personality contrasts with Jack being an esteemed doctor.
Though he's arguably a Co-Lancer with Locke and Sawyer throughout the show, Sayid becomes a sole Lancer during Season 4 when the former pair have split from the main survivors, having the technological knowledge to support Jack's natural leadership skills.
Though Kate acts as Jack's conscience for most of the show, she becomes his Lancer in Season 5 after the Oceanic Six leave the Island, as Sayid drifts away from the rest of the survivors to become Ben's hired killer. Kate is the first person to agree to Jack's proposal that the group lie about the Island when they return to civilisation, and she assures him that she will always have his back, though she does try to talk him out of some of his more reckless actions like returning to the Island, refusing to save young Ben when Sayid shoots him, and detonating the Jughead bomb to prevent the crash of Oceanic 815.
In Season 6, Hurley begins to step up to take a leadership role in the group, with Jack taking a backseat to some of Hurley's decisions as he recognises that he can't control every situation anymore. In the series finale, Jack chooses Hurley to succeed him as the protector of the Island when he heads off to make a Heroic Sacrifice to save the Island and his friends.
Locke also has several Lancers of his own throughout the show.
In Season 1, Boone is Locke's Lancer, being a young, idealistic Heroic WannabePretty Boy who contrasts the older Locke and his Zen Survivor persona, while also getting caught up in Locke's attempts to explore the Island, with the two secretly trying to open the Hatch together. Locke develops a mentor-student relationship with Boone and is clearly devasted by his death.
In Season 2 and early Season 3, Eko becomes Locke's new Lancer. Both have a deep faith in the Island, though Locke's faith is secular while Eko's is religious. Eko is also a powerhouse in a fight, where Locke is more of a stealthy hunter. The two disagree and fight over whether or not to push the button in the Hatch, but Eko is always Locke's go-to partner when he goes mystery hunting.
In Seasons 4 and 5, after they split from the main survivors and when the Oceanic Six leave the Island, Locke becomes The Leader of his own faction with Sawyer as his Lancer. Locke is a straight-talking mystic who is searching for answers to the Island's mysteries, while Sawyer is a duplicitous Con Man who only cares about surviving and regards Locke's faith in the Island and its powers with skepticism. However, Sawyer grows to gain respect and Undying Loyalty for Locke, promising to wait "as long as it takes" for Locke to return when he leaves the Island to bring back the Oceanic Six.
After Sawyer takes over as leader in Season 5 with Jack and Locke both off the Island, Juliet becomes his Lancer, firmly committing to always having Sawyer's back, even when she thinks his "plans" are terrible. This eventually leads to the pair getting together.
Post Heel–Face Turn in Season 6, Ben serves this role to Ilana for a short period before she blows herself up with dynamite. Where Ilana's primary goal is serving Jacob's last will by helping the candidates achieve their destiny, Ben has no love lost for Jacob and is more concerned with the immediate problems of survival and defeating the Man in Black. Ilana also prefers to solve her problems by pointing guns at them, while Ben resorts more to tricks and duplicity.
Noah's Arc: Ricky, as a very clear foil to Noah. While Noah is very moral, relationship-oriented, romantic, and holds the group together, Ricky is much more pragmatic, highly promiscuous, sexually detached, and more than willing to abandon the group over a one-night stand. The stark contrast between them is lampshaded by both of them at different points in the series. Also, Ricky, Noah and Wade are involved in a love triangle highlighted in the movie.
The Office (US): Jim is briefly promoted to co-manager and tries to be a lancer to Michael, tempering his need for fun with a need for work.
Once Upon a Time: In Season 2, Red is this to Charming's Hero, especially with Snow stuck in the Enchanted Forest.
Orphan Black: Felix Dawkins and Alison Hendrix are both lancers to Sarah Manning in different respects;
Felix is Sara's adoptive brother and best friend, most steadfast ally, and the go to guy of all the other members of Clone Club (specifically, Sarah herself, Allison, Cosima, Art, and Krystal) if they have problems even regarding their personal lives.
Alison is the de-fatco Number Two of the Clone Club, as well as being Sara's most decent Foil and voice of dissent within The Team. Her family is also the only other family after Sarah's that is deeply involved/affected with the whole clone conspiracy.
Power Rangers: Naturally, this franchise follows suit. This position is usually held by the blue ranger, but sometimes the green ranger or black ranger hold it. Wes and Jen were a slight twist — they fit The Hero and The Lancer respectively, but Jen was still the official team leader, even after Wes came into his own as a Ranger. Then there's Sky, Dillon...
Revolution: Miles Matheson is the opposite of Charlie Matheson. He's older, smarter, more cynical and more experienced compared to her.
Roswell: Michael frequently plays the classic Lancer to Max's Hero, as both lifelong best friend and, with his loner persona and occasional need for anger management, as his foil. Michael even briefly assumes the role of "king"/leader after Max's "death".
The Secret Circle: Faye Chamberlain is this to both Cassie and Diana during their times as leaders. She was the most strongly against binding the circle and functions as the bad girl of the circle.
Sherlock: As always, John Watson is this to Sherlock Holmes.Sherlock Holmes is a self-professed sociopath who has No Social Skills, treats his allies as idiots, solves cases solely for the thrill of it rather than out of any desire to do good and frequently shows a disturbing appreciation for the macabre side of his work. John Watson, on the other hand, is much more polite and compassionate while also acting as Sherlock's Morality Chain, is more socially adept, and is well-liked by the same friends who hate or are annoyed by Sherlock.
Smallville: Clark has had a few Lancers in the ten seasons of the show. In the first few seasons it's Lex, his best friend and counterpart who is often portrayed as somehow being both Clark's polar opposite and kindred spirit. Once Lex starts to go evil, Oliver takes over the role.
Spartacus: War of the Damned: Three people fill the role: There's Crixus, formerly The Rival of Spartacus and the official Number Two who often question/challenge his authority. Agron, The Reliable One who always stands by Spartacus' side and acts as the de facto Number Two when Crixus is being too emotional to fill the role. And lastly Gannicus, who serves as Spartacus' Foil in every aspect and even shares his fighting style.
Star Trek: The Original Series: Spock is all over this trope. Indeed, he is by all counts equally as competent as Kirk. But where Kirk will go with guts and daring, Spock will always be cool, calculating, and logical. And yes, when the chips are down, Spock is ready at a moment's notice to die for the cause (as seen in Star Trek II). Also, in cases where Spock devoted most of his screen time as The Smart Guy, Dr. McCoy picked up the role.
Star Trek: The Next Generation: Riker was intended to perform the action roles that Picard (as The Captain) really should not be doing. Especially in Season 1, he was a Kirk clone. After Growing the Beard, his role on the bridge was to anticipate Picard's orders and issue them so that the captain wouldn't have to. Contrasts with Picard in Riker being a womanizer (Picard is not very successful with women) and somewhat impulsive (Picard is fairly cautious). Riker also fits the role in easily being the more gregarious and social (he plays in the ship's jazz group and runs the senior officers' poker games) while Picard is the more private and prefers solitary pursuits such as reading and archeology. Oddly enough, while Riker is obviously supposed to be the more physical (being younger and larger) compared to Picard's more intellectual, Picard tends to be the one who ends up in the most physical confrontations over the span of the series and movies.
Star Trek: Deep Space Nine: Kira is Sisko's lancer in every aspect of the trope. If it were up to her, there wouldn't be any Starfleet personnel on the station and she would be in command. In early seasons, she's yelling at Sisko every other episode and often completely ignores his orders when she believes she can handle things better. She grows to trust him in later seasons, but she always remains the person who challenges the captain's orders the most — somewhat unusually, considering that, as the Emissary of the Prophets, he's the equivalent of a saint or prophet of her religion.
Star Trek: Voyager: While he's not the first officer, Tuvok fulfills this role for Captain Janeway. He's calm and rational while Captain Janeway is usually very emotional. In later seasons, Seven of Nine plays the role. Chakotay also has a decent number of lancer qualities: He's the former Maquis terrorist in contrast to Janeway's Starfleet loyalist, and when one of them's being impulsive, the other one usually advises caution. It's not unknown for him and Tuvok to join up to present an alternative viewpoint to her.
Star Trek: Enterprise: T'Pol is definitely this to Captain Archer. She's an officer of the Vulcan High Command on attachment to the Starfleet crew, presents a coldly rational viewpoint in opposition to Archer's more emotional stance (initially as a wide-eyed idealist and later as a bitter cynic), and insists on presenting the strictly regulated Vulcan way of doing things in contrast to Archer's more maverick style of exploration.
Stranger Things: Lucas plays this role in contrast to Mike, acting as an Agent Scully to Mike's Agent Mulder. He's strongly distrusting of Eleven compared to Mike believing everything she has to say and they end up seriously butting heads over their disagreements, especially when it comes to her.
Their rivalry also comes up when they have a much more light-hearted disagreement in the second season. Both of them decided to dress as Peter Venkman for Halloween. Mike said that there can't be "two Venkmans" and that he thought Lucas was going to be Winston despite Lucas "specifically agree[ing] not to be Winston."
A rather unique twist of The Lancer concept is given in Samurai Sentai Shinkenger. Our hero Shiba Takeru (Shinken Red), is The Stoic. Then, we have the rebellious Sour Supporter Tani Chiaki (Shinken Green). Most people would call him The Lancer for being rebellious, but turns out he's The Smartass Kid instead. The Lancer turns out to the Extraordinarily HammyYes-Man Ikenami Ryuunosuke (Shinken Blue), not only because he's Takeru's second in command, but his personality is quite the contrast to Takeru. So, yeah, Ryuunosuke is definitely 'Hammy, hyperactive Lancer done right'.
Top Gear (UK): Richard Hammond to Jeremy Clarkson. Hammond is a head shorter, a decade younger, and physically tough but emotionally fragile compared to Clarkson, yet they are inseparably bonded by a mutual love of fast, powerful cars. The third presenter, James May, acts a bit like a Lancer to Clarkson but they are more of an Odd Couple.
Torchwood: Owen falls under this fairly well, at least in series 1. Owen is The Lancer to Gwen while Jack is away. When Jack returns, Gwen becomes his Lancer.
The Walking Dead (2010): Shane Walsh for the first two seasons. Daryl Dixon from Season 3 onwards. Until Season 3, Andrea is this to Lori for the women. Michonne also becomes one to Rick starting the second half of Season 4.
The West Wing: Leo is a dead-on Lancer of the Blue Oni type to Bartlet's hero. Being The Lancer is also Josh's calling in life, according to Bartlet: "You know the difference between you and me? I want to be the guy. You want to be the guy the guy counts on." In the later seasons other characters lampshade the fact that Santos, to Josh, is his opportunity to be what Leo was to Bartlet.
: Tegan is moaning because she doesn’t like the idea of Turlough traveling with them (and no its isn’t because she wants the Doctor all to herself, pipe down all you shippers at the back!) ...It's true that she is at least very honest, there is nothing that she would say behind Turlough’s back that she wouldn’t say to his face. More’s the pity: because now we have to listen to it twice. Then once all the bile is extracted from her gut she turns round and tells Turlough that he should stay! You know when hackneyed male figures in fiction stick their hands on their hips and cry ‘women!’ at something exasperating? I think that should be adopted here but the word changed to ‘Tegan!’