He's also this as Jason in Battle of the Planets. Mark definitely deserves sarcasm. Sometimes one wonders about the devotion.
And Dirk from G-Force: Guardians of Space follows the traditions of his predecessors.
Shinichirou Tamaki, one of Lelouch's lieutenants in the first season of Code Geass, who is nonetheless one of his most useless servants.◊ A more benevolent variation is C.C., who often doubts or mocks Lelouch and his plans, but always goes along with them anyway.
Shirin Bakhtiar, Princess Marina Ismail's advisor in Gundam 00. Although we never really saw enough of that pair to see what her real deal was, some viewers got the impression that she was stringing Marina along for her own purposes. Plus, she leaves in episode 25 (leaving Marina looking rather upset) but not before the Celestial Being incident is resolved and Azadistan is apparently on its way to solar age.
Atsuyu from The Twelve Kingdoms is the governor of En's biggest and richest province, and is rather cynical in regards to the new king Shoryuu. Horribly subverted when we learn that he's not a devotee, but a Smug Snake who wants to depose Shoryuu and become king.
Tomoe from Kamisama Kiss is one-hundred percent loyal to Nanami while at the same time is extremely sarcastic towards her, highly critical of anything she does and tends to fight her every step of the way. It doubles as a Hypocritical Heartwarming since he doesn't let anybody else behave like this towards her.
Zenkichi from Medaka Box is always going on about how he's fed up with Medaka and her stupid plans, that this is the last time and he won't be helping her again, that he is tired of it all... but he always comes back to her and has vowed never to leave her side. His basic reason for living for the entirety of his life has been helping Medaka... Usually by keeping her in check because Medaka really has no clue how normal humans think or act and is constantly doing insane things.
(Modern) England from Axis Powers Hetalia could be interpreted as one to America; the two countries have some of the strongest military ties in the world, and England is definitely sarcastic and critical enough to America to qualify on that aspect.
All the Straw Hats are this to Luffy in One Piece at one point or another. They frequently insult their captain who has made some silly or strange decisions that they don't agree with but are all incredibly loyal to Luffy and wouldn't hesitant to fight or even die for him.
Hawkeye of The Avengers embodies this trope so thoroughly, he's almost a better example of The Starscream. For years, he served under the leadership of Captain America and disputed every judgment call wing-head made; no matter how trivial, and never failed to punctuate his complaints by claiming that he would make a much better leader. Even after Hawkeye got to lead his own team of Avengers, these arguments still cropped up every time he had to step back into a supporting role.
Iron Man was a more laid-back form of this as well in the team's classic incarnations (as he tended to usually shrug and fall in line if he wasn't listened to), with his style of devotee sarcasm being more "dude, stop yelling at me I agree with you", "no, your problem is dumb and you're just whining", and "wait wait you forgot about X" when Cap got a little too caught up in the problem at hand, had crises of faith, or was too idealistic.
Batman's trusted butler (and surrogate father) Alfred is perhaps one of the most infamous of such characters.
Strongbow in ElfQuest. Spends a lot of time questioning Cutter's authority as chief, challenges him for leadership and loses, and later even walks out on him for a while. But when he's needed in a crisis...
In Ultimate Marvel, Tony Stark/Iron Man's butler, Jarvis. Until he, y'know, died.
Similarly, evil Mojo's butler and right-hand man, Major Domo, often comments on his very dangerous boss' craziness and round physique.
Captain Haddock often makes sarcastic remarks about The Adventures of Tintin's goody twoshoesness (and the trouble it sometimes gets them into), but will never abandon him.
In X-Men, Wolverine serves this role towards Cyclops. For a while in Wolverine's own book, Jubilee was his very own Sarcastic Devotee.
Films — Live-Action
A good part of Cube is spent establishing Worth as a villainous character - and he is indeed eventually revealed to have some relation to their predicament - but in the end, he proves to be more heroic than de facto The Captain Quentin.
Sir Robin's faithful minstrels in Monty Python and the Holy Grail. "Bravely taking to his feet - He beat a very brave retreat, - Bravest of the brave, Sir Robin!"
The Iron Man franchise has this in the form of J.A.R.V.I.S., Tony Stark's AI he built, who constantly snarks at Tony's often poor choices, and in the third film made a safety protocol "for you to entirely ignore".
The 2009 Star Trek has Spock, very much like his Original Series counterpart, be this towards Kirk. Helps that the two really didn't like each other when they first met.
Spock: "I would cite regulation, but I know you will simply ignore it."
Captain Hastings, Hercule Poirot's early Watson. Once, Poirot failed to solve a mystery involving a box of chocolates. After that affair, Poirot tells Hastings that if he ever acts too conceited, he should use the words "chocolate box" to bring him down a peg. Poirot isn't amused when Hastings uses the code words mere seconds later.
A truly odd example from the Artemis Fowl series. Opal Kobai can apparently mind control the doctor in The Time Paradox, but while it does make him follow her orders, he snarks and complains the whole time.
Sancho Panza, who is constantly picking up after Don Quixote's misadventures. Deconstructed by Sancho Panza: What happens in Real Life to the employee that cannot say anything about his master without being sarcastic? Why, Sancho is beaten by Don Quixote at chapters XX and XXX of Part I, and gives him a hurricane of insults at chapter XLVI.
On hearing this Sancho, who had been listening with great attention, cried out in a loud voice, "Is it possible there is anyone in the world who will dare to say and swear that this master of mine is a madman? Say, gentlemen shepherds, is there a village priest, be he ever so wise or learned, who could say what my master has said; or is there knight-errant, whatever renown he may have as a man of valour, that could offer what my master has offered now?"
Don Quixote turned upon Sancho, and with a countenance glowing with anger said to him, "Is it possible, Sancho, there is anyone in the whole world who will say thou art not a fool, with a lining to match, and I know not what trimmings of impertinence and roguery? Who asked thee to meddle in my affairs, or to inquire whether I am a wise man or a blockhead? Hold thy peace; answer me not a word; saddle Rocinante if he be unsaddled; and let us go to put my offer into execution; for with the right that I have on my side thou mayest reckon as vanquished all who shall venture to question it;" and in a great rage, and showing his anger plainly, he rose from his seat
Doctor Watson, towards Sherlock Holmes, though usually only within the text of his own narrations, and normally about more minor things rather than major conflicts. He knows better than to question Holmes's judgement during cases, but has few compunctions about taking potshots at Holmes's irritating habits and predilections.
Agent/Colonel John Casey from Chuck does this exceedingly well.
"Captain, you are an excellent starship commander, but your driving leaves much to be desired."
It would seem unflinching loyalty wrapped in deadpan snark is one of the Vulcans' many hats. T'Pol and Tuvok are both like this as well.
Bones McCoy, who as Captain Kirk's chief medical officer and close friend is basically the only one on the ship with the license—and the chutzpah—to question Kirk's judgment openly. Spock is more polite and guarded.
Geoffrey Butler, the butler in The Fresh Prince of Bel-Air, and Florence, the maid on the The Jeffersons. Both stick with their employers despite hating them and having other options. (Ok, so Geoffrey leaves once, but it was just to make a point.)
Florence left once too but her spinoff show was cancelled I guess she decided to come back.
Although she and George don't get along she and Louise are close. Deep down she and George also like each other but never admit it.
Anyone who sticks around on Serenity becomes one sooner or later because, let's face it, Mal has it coming. Both the devotion and the sarcasm.
Benson, the Tates' butler on Soap, who only sticks around to take care of Jessica Tate.
And then, Benson keeps doing it when he goes to work for the governor in Benson.
And so does Maxwell's butler in The Nanny. I think I see a trend...
A few of the Doctor's companions will occasionally point out the flaws in his plans, and in extreme cases, question his competence. This seems especially prevalent in the new series, as basically all the companions have done snarking on the Doctor's behalf.
Two words: Donna Noble, with her habit of calling the Doctor "Spaceman".
Amy Pond on the Doctor being a Time-Lord; "That's just what they're called, it doesn't mean he knows what he's doing."
Tegan Jovanka, a companion of the Fifth Doctor never hesitated to tell the Doctor off.
Averted by Katarina in "The Dalek's Master Plan" and likely the reason why she was quickly bumped off. A Companion who views the Doctor as a god isn't any good for the series.
Toby Ziegler on The West Wing, whose snarking and complaining are actually things that President Bartlet highly value.
[Future!Dean has just suggested a suicide attack, and objected to Cas's description of it as "reckless".] Future!Cas: If you don't like "reckless", I could use "insouciant", maybe. Future!Dean: Are you coming? Future!Cas: Of course.
This is Avon from Blake's 7 to a T - even after Blake disappears.
Debatable. Avon shows some traits of this, but on numerous occasions he goes beyond sarcasm and into power games, trying to undermine the crew's support for Blake. He also takes the ship away to protect himself more than once, when Blake is counting on him to teleport them to safety.
He seems to be tied to this trope by a piece of elastic; the farther he stretches (taking the Liberator away) the harder he comes back (and ends up rescuing everybody). It depends how seriously you take his intentions — it is worth noting that when his actions did have bad consequences for the others (and Blake) he actually felt guilt about them.
Dark Oracle: Simone is one of these to Vern, whom she may or may not have a crush on. No matter how moronic Vern's plans are, Simone sticks by him, mocking him the entire time. She finally leaves when he goes completely overboard and orders her to get lost.
Dick the Butcher from Henry VI Part 2: During the speech when rebel leader Jack Cade claims he's rightful heir to the throne, Dick gives scathing asides mocking the veracity of these claims. However, after the rebel uprising, he's singled out by Cade for being the man with the highest hit count. The Butcher indeed.
Although less so if the player is doing well. In that case he saves his sarcasm for Slippy.
A villainous example in The Witcher: Azar Javed's Dragon, The Professor, criticizes Azar in messages and openly berates him in combat, but is always there on command and follows orders, likening himself to a summoned genie. He stops short of being The Starscream in that he never considers betraying Azar, even when he's up against a wall with his life at stake.
Etna from Disgaea is the only one of the late king's vassals willing to serve Laharl, and she's quite sarcastic to him, since he's a Royal Brat. Even though she uses him as bait to stop Maderas, she genuinely feels guilty about doing so, since she promised the king, the only person to ever show her kindness, that she'd protect his son.
In the sequel, she leaves him after a fight, but she returns to him after Flonne gets them to make up and apologize.
Pink in Dark Hero Days constantly makes thinly veiled insults towards Axel, but he's completely oblivious to them. Fenrich in Disgaea 4 also makes insulting remarks towards his master Valvatorez, but he doesn't seem to care, either.
In Persona 3, Shinjiro Aragaki is brusque and standoffish with the male protagonist, telling him not to try to tell him how to fight and snarking at him in combat when, for example, the protagonist heals him ("Tch. I don't need your help.") or gives him an order ("Who does he think he is?"). It's mostly a front (and he's noticeably less belligerent toward the female protagonist).
Tails has mild shades of this in recent Sonic the Hedgehog games, he makes the odd bewildered or exasperated remark towards Sonic's wackiness but otherwise is a devoted friend and right hand man.
Lydia is one of the strongest followers in Skyrim, but sarcastically says "I am sworn to carry your burdens" whenever you use her as a pack mule.
In Ratchet & Clank, there's Dr. Nefarious' henchman Lawrence, who does this a lot, often making subtle insults about how stupid his boss can be. (And Nefarious never gets the hint.)
Lampshaded in Final Fantasy XII. Basch asks Balthier why he's still tagging along with the Princess for seemingly no reason, especially since he likes to snark at her and undercut her authority on occasion. He doesn't really give a straightforward answer, but by the end of the game, he's perfectly willing to pull a Heroic Sacrifice to save Ashe's kingdom.
Archer from Fate/stay night, though he subverts it in Unlimited Blade Works. And on the villain-ish side, Assassin plays this role towards his master, Caster.
Everyone in Something Positive is like this: they'll snark each other to shreds, but are fiercely loyal to each other.
Nodwick's title character, as well as the henchmen in general. Although nominally bound to his party due to his draconian labor union laws, Nodwick does actually care for them (mostly, anyway).
Piffany, at least. If Artax and Yeagar were to let up on the abuse he probably wouldn't cry I want my jerks back anytime soon.
Every sidekick in Girl Genius strays into this territory now and then for comic relief. But Moloch (a soldier and mechanic who's bitterly aware of the life expectancy of sidekicks in this world) and Violetta (a bodyguard who's convinced that her charge is suicidally stupid) are permanently unimpressed with what the main protagonists are doing.
Gil Wulfenbach can be like this at times (especially in regards to his father's employee relations methods compared to his own), and he's one of the madmen people sidekick at.
Of course, since he was elected as Optimus' second should something happen, this makes his loyalty to Optimus as much self-preservation as anything.
Kiff of Futurama sticks behind Zapp Brannigan no matter what (probably because it's his place in the military), but makes it painfully obvious that he hates Brannigan for it. Oddly enough, Zapp is never fazed by Kiff's commentaries.
Being a moron, it's likely that Zapp isn't aware that he's being mocked.
That and he just thinks Kiff is a massive coward -which, to be fair, isn't far off the mark.
It seems to go beyond his line of work, even when they were both fired from their ranks (almost entirely because of Zapp) Kif still acted like his usual submissive (but sarcastic) self towards Zapp despite no longer having any power around him.
Sokka is arguably the better example because it's actually part of his Character Development. Throughout the first 2 seasons, he constantly questions both Aang's and Katara's judgments, making sarcastic quips concerning their Chronic Hero Syndrome and their reliance on Bending and anything mystical. By the third season, he almost completely grows out of this, coming to fully trust in Aang.
Gwen was this to Ben in the original Ben 10 series: she constantly argues with him, insults him, criticizes his immaturity... but if he is in danger or in an actually messy situation, she will be there for him. The sequels Ben 10: Alien Force and Ben 10: Ultimate Alien toned down the Sarcastic aspect, though it's still present on occasions.
Hawkbit from the T.V. series of Watership Down. Even at one point, Hazel finally (and calmly) tells him: "We can deal without the sarcasm, thanks."