Played straight, parodied, played for laughs, lampshaded, and justified with America in Axis Powers Hetalia. As he is the (admittedly stereotypical) personification of the US, he is deeply loyal to it. He hates Communists and Nazis, and claims, "I'm the Hero!" However, he is completely clueless (giving him the nickname AKY in the Japanese fandom, short for Aete Kuuki Yomenai, which roughly means "Doesn't read the atmosphere") and orders his allies to be his backup. *
Although, perhaps his ego is a little justified considering he was swinging a full-grown bison over his head. As a baby.
Played with in one of the Mobile Suit Gundam sourcebooks, styled as a collection of news photos from the One Year War, featuring a shot of war orphans watching a Captain Zeon cartoon.
Captain America, aka Steve Rogers, is the most famous, and greatest embodiment of this trope ever. If you need to sum up his deepest values with one line, it's "I am loyal to nothing...except the [American] Dream."
Ultimate Captain America to Commie Super-Soldier: Yeah, I'm gonna fight you. You know why? Because I fought beside Russians during World War 2. They were good and decent men, and they made terrible painful sacrifices to save their country. And for their country to then turn around and put monsters in prisons with nuclear landmines... to see people like you, proudly complicit in this nightmare... Yeah, I'll fight you. You've waited forty years for me in this hellhole, I feel it'd be impolite not to kick your head in.
Marvel has a few other examples: Miss America, Citizen V, Josiah X or Patriot from Young Avengers(the latter two are actually the son and grandson of one of the guys to wear the mantle of Captain America after Steve Rogers).
Also the Superpatriot/USAgent, the original Patriot, the Spirit of '76, the Defender, Jack Flagg, the Free Spirit, American Eagle, etc. The first three especially, since at one point or another they were Captain America themselves!
Of course, there's dozens of failed attempts at replicating the Captain America formula for success (or prototypical attempts that didn't fare well either). Anti-Cap (the Navy's Super-Sailor), Protocide (Failed early attempt), GI Max, Nuke, the 50s Cap who went crazy, etc.
Another Marvel example is Captain Britain, who stands for all values of England, and all his alternate counterparts do the same - the only Evil Twins he has are from worlds where England is an evil empire. Such as Captain Airstrip-One, the ultimate government tool with nothing resembling a will of his own. He fights for the glory of Ingsoc.
And we cannot forget about Falcon, the biggest Captain Patriotic not dressed in the flag.
And other people who were carrying the name of Captain America, like Patriot's grandfather, 1950s Cap or Bucky (who, in an inversion of Captain Geographic, wore a costume that looked more like the flag of Puerto Rico).
Captain America's original costume, bearing only one star on the chest and back, looks more like the flag of Liberia than the Stars and Stripes. At least Puerto Rico is US territory!
James MacDonald Hudson once pointed out in discussing his own costume that Cap's costume was meant to be a loose interpretation due to U.S. restrictions on flag-wearing, while his own costume as Weapon Alpha/Vindicator/Guardian was essentially the Canadian flag wrapped around him.
And then there's Black Panther, the king and national hero of the African nation of Wakanda.
Doctor Doom could be considered a villainous version of this trope for his nation of Latveria. Ironically, in-universe, the people of Latveria -like- him and think of him as a good ruler as while he may be a tyrant, he honestly thinks of his country and people as his own and protects them/provides for them as such.
Another villainous Captain Patriotic was the Tarantula, who was hyped as this trope but was mainly The Dragon to the murderous dictator who ruled his South American country.
Marvel's version of Germany has Hauptmann Deutschland, which translates as "Captain Germany".
Archie Comics character The Shield, created fourteen months before Captain America, brought back for a while by DC Comics.
Canada has Captain Canuck.
Dozerfleet Comics has Centipede Charlie and the Gray Champion, as well as Anarteq and Becky Ryba. However, they're more like subversions than straight examples.
The Gray Champion doesn't necessarily fight for America. He fights for those values of America's Christian past in its colonial years that he agreed with back then and continues to into the 21st century - even when a third of the nation itself rebels against those values, and ends up ripping the country apart as a consequence. The seceding states he has the fewest disagreements with are the ones he ends up protecting, letting the others freely choose their own paths to destruction. He reasons that it's a waste of time trying to help those who are that far lost when they're that dead-set against helping themselves. They don't want the truth, especially not from him, in the first place. Any effort to help them would only distract him from offering help to those who'd actually value it.
Becky Ryba is a patriot without a country. She is impressed into the program simply because she's a Phexo, though she doesn't feel particularly loyal to any nation in the war. She particularly cannot appreciate her native Russia after the Russian Revolution.
Anarteq is Canadian, but cares more about flirting with women and celebrating his Eskimo heritage than singing the glories of being Canadian.
Centipede Charlie only fights for America so he can negotiate for his girlfriend's release from an internment camp. He cares nothing for how the military or Phaelites are cynically manipulating him.
In Stormwatch: Team Achilles (the Wildstorm Universe, Earth-50 of the DC Multiverse), Citizen Soldier is so much a super-patriot that he renounced death itself to protect America. In fact, he's George Washington (yes, that George Washington), constantly reincarnating thanks to a magic ritual designed by Franklin, Jefferson, and the other Freemason sorcerers.
Nedor Comics had a few of those, like Liberator and American Eagle, but its best example was Fighting Yank, powered by the American Spirit itself and with the ghost of a World War I hero as The Mentor. Since Nedor's characters fell into the public domain, they've seen several revamped uses in recent years, including Terra Obscura and Project Superpowers.
Fighting American, who quickly turned into parody when Joe Simon and Jack Kirby realized he was not as popular as they expected. Even when Rob Liefeld bought the rights to this character in order to turn him into a Captain America rip-off it didn't work.
DC's Spirit of America went through a metamorphosis from Minuteman (Revolutionary War) to Brother Johnathan (antebellum period), then splitting into Billy Yank and Johnny Reb (the Civil War), then merging again and becoming Uncle Sam (post-Civil War to today). Well, okay, he was also briefly the Patriot circa 2002, but went back to Uncle Sam after only one or two appearances in that form.
Wonder Woman was this initially, but her character has developed significantly over time. In her first stories she was a foreigner dressed in a costume that Americans would interpret as "patriotic", apparently as conscious propaganda.
American Eagle in Captain Carrot And The Final Ark is a parody of the trope; a right-wing radio host who talks entirely in patriotic cliches. He has no powers "except those granted to me by the Constitution".
Image Comics has Super Patriot, who was in his heyday a direct Captain Ersatz version of Captain America. His kids with the superhero clone names Liberty & Justice also qualify.
In Rising Stars, corporate superhero Flagg (who later changes his name to Patriot), is working on his reputation as one. However, the real Captain Patriotic in this universe is officer Matthew Bright. Bright wanted to serve America and its people so much he joined the police force. He has to hide his powers, because Specials cannot be members of any force. And when the government found out and was trying to kick him out, his fellow police officers protested so much, they had to give up and try to use a Legal Loophole to forbid him from wearing a police uniform and badge, thus making it impossible for him to work. They underestimated his friends from the Police Department, who just brought an uniform and badge designed only for him.
PS238 had several examples. They have a Captain America clone, Freedom Fighter, hanging around, but he's not immortal, and is nearing retirement. Both the Republicans and the Democrats are grooming their own 'Replacement' flag-waver: US Patriot Act and American Eagle. Their constant attempts at out-patriot each other are obnoxious, the constant quarreling prevents them from accomplishing much of anything, and instead they cause trouble for anyone hanging around. Political commentary? Where?
Superman. "Truth, justice and the American way." Superman, being an alien, adopted the USA as his country.
Spoofed in the Saturday Night Live sketch "What If?". With the statement, "What if Superman had grown up in Germany instead of America?". Superman becomes Uberman.
Done deadly serious in Kim Newman's "Ubermensch!".
And Superman: True Brit, in which he is raised by an incredibly bland and none too bright British family; he's still a defender of Truth, Justice, and the British Way, but is kind of a nitwit.
Overman of Earth-10 is an aversion - a Superman adopted by Nazi Germany in a world where the Nazis went on to win World War Two, who has abiding guilt over their atrocities.
A different Overman (a native of the Darker and Edgier Earth-17) wore an American flag cape.
Earth-23 has a black Superman who, in his secret identity, became US President. Naturally enough, solicits and fans call him President Superman.
In JLA-Avengers Superman had to carry Cap's shield at some point. He felt honored.
Socialist Red Guardsman of China's Great Ten. While August General in Iron and Immortal Man in Darkness are also true patriots, Socialist Red Guardsman is the only member of the team to actually have Das Kapital and The Little Red Book committed to memory. Socialist Red Guardsman believes he is the revolution, and has frequently broken his back to ensure that his teammates toe the party line with his endless rants and lectures. He even attempted to quit the team in disgust at his country's growing commercialism.
Tomorrow Stories features the parodic First American and his sidekick U.S.Angel as it is, but one issue sees FA consulting with other national heroes - Captain Uzbekistan, Le Premier Francais, Deutschlander Zahlein, and the Fightin' Limey ("who sleeps in my garage").
Parodied with CapitŠn Hispania, who carries a shield with the colours of the Spanish flag, but never says anything that can be considered patriotic.
Tarn from Transformers More Than Meets The Eye is wholly devoted to the Decepticon cause, fully believing in Megatron's Peace through Tyranny (He named his ship the Peaceful Tyranny). So great is his devotion, he grafted the Decepticon symbol onto his face.
In addition several ships, Worldsweepers, are in the shape of Giant Decepticon symbols, flown by the most powerful or loyal, and they're so big, even from space, one sees them and knows, this is a Decepticon controlled planet.
"I don't know what will come from all of this, but I must use these new powers to help my country fight her enemies - within and without. Those reds might have killed Frank Stiles, but they're about to meet... The Minuteman!"
He also happens to be a Genius Bruiser, having been a nuclear physicist working on the Manhatten Project.
The Gerosha expanded universe has the Gray Champion, based on Hawthorne's character. More about "God" than "country," he takes the "God and Country" thing very seriously. Almost too seriously some times.
Which actually helps balance him somewhat. Unlike Ciem, who is always worrying about her family and her sexual problems, Gray is already mature and nearly beyond having such concerns. It also gives him a compass to control his emotions, so he doesn't degenerate into the Emotion Eater, Reality Warper, Ax CrazyAnti-HeroNoble Demon that Extirpon is.
In the Global Guardians PBEM Universe, there's Captain Texas, Ultra-Man, the Citizen, Doc Liberty, Independence, Uncle Sam, and every single member of the Arsenal of Democracy.
Interestingly enough, the otherwise appropriately-named hero known as "The Patriot" is not a Captain Patriotic, as he is themed after the New England Patriots football team, and not on patriotism. Despite the correct color scheme, he's definitely Captain Sporting-Goods, not Captain Patriotic.
Major Glory from Dexters Laboratory is a spoof of this. He even hawks a snack named "Justice Fruit Pies," and periodically recites lyrics or lines from famous American works (such as the national anthem, the Constitution, and the Pledge of Allegiance). However, the jabs are entirely affectionate.
In the Mr. Incredible and Pals spoof on the The Incredibles DVD, Mr. Incredible is portrayed as one of these.