Specifically, Goku himself fulfills the trope by being the best man you'll ever meet or hear of, but will focus on his training to the exclusion of everything else, sometimes including family. This is justified by Earth coming under regular attack by superbeings both terrestrial and extraterrestrial, and the fact that Goku is, in practice, the Big Good of the universe at the end of the series (he's kinda busy sometimes).
Maka Albarn from Soul Eater eventually becomes this. She starts out a bit short tempered, but over time, becomes a responsible, courageous, strong, caring, kind, honorable, intelligent and selflfless young girl.
Definitely Fudou Yuusei from Yugioh 5 Ds. He wins every duel, is level-headed, always plays by the rules, always looks out for those in trouble, and generally ends up being liked by any non-villain who holds more than three minutes of conversation with him.
Digimon Xros Wars: Taiki Kudo would count. He lives to help anyone in need, and refuses to "turn his back on anyone", and strongly believes in the good of people and digimon.
Daiya Tsuwubuki of Gaiking: Legend of Daiku Maryu always fights fair, never loses sight of his goal, and always tries to help people in his actions. He never uses deception or trickery, and despises those that do.
Superman, consistently, but given an especially provocative portrayal in Kingdom Come, where Superman plays this trope straight, subverts it, and reconstructs all over the course of the story.
In fact that ends up being the way they challenge the Invincible Hero in many of his better stories, putting things in front of him that could legitimately compel him to break this character type or putting him up against less ideal sort of hero (frequently Batman) to make a case for being an ideal hero versus being a more "pragmatic" hero. Some of his most crippling defeats were victorious battles that could only be won by breaking one of his rules.
Little wonder, then, that the two would be combined into the character Super-Soldier in the Amalgam Universe.
Spidey is mostly this in his own series and team ups, aside from doubting himself, being a goofy motor mouth and being generally awkward, he is Marvel's most lovable and warm hearted hero who always does the selfless and right thing for anyone and anything in his career only second or rivaling the Captain himself and in the future is destined to be the greatest hero of all according to Cable.
Tintin, a teenage detective/reporter. He'd risk his life to save yours, even if you just tried to kill him not five minutes prior; he's just that noble and uncompromising on his principles. In spite of being that forgiving towards his enemies, he's also a textbook case of Good Is Not Dumb.
AstÚrix is one of these - kind, does the right thing all the time, won't fight physically unless there are no better options even though he has super strength, always stands up for people who are suffering, and plays by the rules. However, he also has a sneaky side, especially in earlier stories.
Power & Glory is all about playing with and subverting this trope. While A-Pex may resemble an all-American superheroic ideal, it's all a media manipulation job by his government creators, and the real person is far from an ideal anything.
R. A. Salvatore's Forgotten Realms character Drizzt Do'Urden, the heroic dark elf ranger who rebelled against the evil of his people and fled to the surface world, where he had to overcome a huge amount of prejucide, but always remained unquestioningly true to the ideal in his heart that made him rebel in the first place.
Although not the main character, Carrot Ironfounderson from the Discworld series is a walking paragon of an Ideal Hero
Although Solomon Kane is typically classified as a Anti-Hero, he could arguably fall under this instead. He never compromises his princples, nor does he question what the proper course of action is when he encounters someone who needs help (or, if they are beyond help, someone who deserves to be avenged). In The Blue Flame of Vengeance, he even tries to talk one of the villains into giving up the fight and walking away from the evil men said villain has entangled himself with; when the villain refuses to accept his offer and subsequently dies, Solomon becomes visibly grieved.
King Arthur and Galahad definitely, and a lot of the other knights of the Round Table come close.
Simona Ahrnstedt usually gives her characters some flaws, even if they're not villains. And the only male exception is Johan Stierneskanz from Íverenskommelser. He's basically perfect and flawless, the lily-white Nice Guy in a story with three jet-black villains.
In the series Acacia the Acacian prince Aliver Akkaran - the man is compassionate, honours his word, forgives his enemies without hesitation...etc. He dies for that, but gets better in the end before dying again though not before reforming the Acacian empire and bringing world peace
Live Action TV
Most incarnations of the Doctor. Fourth and Fifth are probably the most obvious ones.
Constable Benton Fraser on Due South is the ideal Mountie in every possible way.
Captain Picard of Star Trek: The Next Generation is the pinnacle of 24th-century enlightened humanity, to the point that he's chosen as their representative when Q puts the species on trial. He favors diplomacy to force whenever possible, respects all forms of life, has no greater desire than to learn and explore, and knows exactly when to disobey the Insane Admiral or violate the Prime Directive.
An argument once given in the eternal Kirk vs Picard debate was presented as such: Kirk is the kind of Captain and leader who many people would love to go on an adventure with and have a beer with afterwards, Picard is the kind many would willingly follow right into hell itself.
The song Holding Out For A Hero by Bonnie Tyler may possibly be describing one of these:
Where have all the good men gone and where are all the gods? Where's the street-wise Hercules to fight the rising odds? Isn't there a white knight upon a fiery steed? Late at night I toss and I turn and I dream of what I need...
Dino Attack RPG had quite a few such agents, especially early on. Zenna, Rex (at least, prior to the Adventurers' Island arc), Andrew, Zachary (pre-Stromling), and David being good examples- and that's just among primary characters. Pierce could also be considered an example, although justified by the fact that he's a doctor.
Fate/stay night: No matter what the route, Emiya Shirou tries to be an Ideal Hero. However, the story challenges the idea of the ideal hero and whether it's really an attainable goal for any psychologically normal person. The answer it comes to is no, not really, and it won't make you happy to be one either. It's still an admirable goal even if you can't do it, though, and even the bitter Archer (an Alternate Future version of Shirou) still finds the dream beautiful.
His adopted father Kiritsugu further deconstructs this trope, as he learned throughout his years as a Hitman it is impossible to save everyone. His goal in the grail war is to make the world a better place, too bad it was all in vain.
Ferwin and Pyan Pau in The Spirit Engine 2. Charlotte seems to be this at first, but is actually a subversion.
The Hero of the Quest for Glory series can be played this way, while The Paladinis this trope. The player is outright told by Rakeesh that the Paladin must do what is right, even if the right thing to do isn't lawful (in Quest for Glory III he breaks the law to give food to a convicted thief). His powers are also based around honorable behavior (doing good deeds, being honest) and performing dishonorable acts will cost him the use of his abilities.
Leonhardt Raglen in Record Of Agarest War is the most heroic protagonist out of the entire series as he is selfless, responsible, all-loving, willing to sacrifice his life for a little girl who is hunted by his very own nation, and is Badass enough to kill the guy who killed him in the first place.
Skyhawk, one of the superheroes of Boston in the Whateley Universe. He always tries to do the right thing, and stands for morality and righteousness. Most of Team Kimba views him as a big dork, and his determination to do things the right way very nearly got Generator and Bladedancer killed by supervillains.