Austin of Austin & Ally: Even if he screws up sometimes, he is nice to a fault. He's sweet, gentle and when he comes to understanding the feelings of others if he has hurt them, he will try his hardest to make up for it. Go look at the Heartwarming page for examples.
Black Mirror: Cooper from "Playtest". For once we get a Black Mirror protagonist who isn't a Villain Protagonist or an awful person in need of a lesson, but instead we get a quirky, friendly and well-adjusted guy who's only flaw is not checking back with his mother. This makes his horrific fate by technology-induced Mind Rape all the more tragic.
The Boys (2019): Starlight, who is all around sweet, kind and everything a superhero is expected to be. Hughie even calls her this to her face.
It has Dr. Rich. A Nice Guy who can't hold a grudge. He volunteers once a month in Central America to fix cleft palates, cleans up rivers, and teaches seeing-eye dogs. In his free time he makes kettle corn and takes pottery classes to unwind from the pressures of his job, he hasn't lost a patient in five years. Oh, and he'll also show you how to check for breast lumps.
Season 3 gives us Todd, a loving father and retired Marine whom everyone hates.
In the main cast, Troy is the only one who's never been given any serious social flaws, and has never been cast in a villainous role.
Jimmy from early Degrassi: The Next Generation — he's almost like a medieval knight, in being both a perfect gentleman and somewhat clueless and stiff. He loses his girlfriend to a sensitive Emo Teen who understands emotions better, and his honor code means that he refuses to participate in gang bullying, but is utterly ineffective at stopping the bullying.
Rory Williams of Doctor Who. A nurse who became the Victorious Childhood Friend to the Doctor's companion, Amy Pond. Of course, his nice guy attitude allows him to act as an interesting foil for the Doctor. Besides, if you hurt his wife you better Beware the Nice Ones, because you've now got the 2,000 year old Last Centurion on your tail.
Due South: Benton Fraser of the Royal Canadian Mounted Police. He's so friendly that he will miss elevators so that he can allow others to ride first (which made the opening credits) and his tenement neighbors are immediately suspicious of him since he smiles and goes out of his way to know all of their names. His trademark response is to treat even people who are in his face yelling at him in anger with such incredible curtesy that their anger is defused.
Euphoria: For all her hedonistic and self-destructive behavior at times, Jules is a kind and sweet young lady.
Ross is Adorkable and romantic. He becomes a good father to his son Ben and his daughter Emma and he manages to get on well with his ex-wife Carol.
Joey is incredibly loyal and a great friend. He manages to be a good guy despite his womanizing ways.
Chandler, despite his sarcastic defence, is a total sweetie, constantly puts his friends and later girlfriend ahead of himself, and comes out with some of the most thoughtful moments in the series.
Phoebe's husband Mike is a sweet generic guy who loves Phoebe and enjoys taking care of her. He doesn't mind that his upper-class family frowns upon their relationship.
Phoebe's first serious love interest, David "the Scientist Guy". He's a cute geeky guy who is crazy about Phoebe and would do anything for her. Too bad his career takes him to Minsk and they are separated.
Ross and Monica's father Jack Geller is a good man who loves his family. His only fault is that he did not notice his wife Judy definitely favoured Ross over Monica.
Monica's season 2 boyfriend Richard Burke is one of the nicest characters on the show. It's lampshaded by Chandler, who tells him that he's a good guy. Richard replies that he hates that.
Renly Baratheon is the only man who has treated Brienne of Tarth with kindness and respect, and he's probably the only king who has accepted a woman into his Kingsguard. He does this despite knowing full well that it would shock his bannermen, annoy his wife, and piss off his lover. He himself understands how painful it is to be frequently mocked for not adhering to rigid gender roles (his older brothers Robert and Stannis have bullied him for his lack of combat experience), so his empathy towards Brienne's situation allows him to be accepting of her masculinity. Renly praises Brienne's martial skills and her devotion when his boyfriend Ser Loras Tyrell confronts him about it. Margaery Tyrell describes her husband as "brave and gentle" in "Dark Wings, Dark Words." This is a notable deviation from the books. Some people question if Renly is really that nice in the show, considering his mocking behavior towards his brother and his willingness to kill them so he can win the throne and his hypocritical claims to Catelyn that he is a natural ally to the Starks, despite him leaving Ned Stark to be killed by the Lannisters.
Amidst the Loads and Loads of Characters on the show, you could count the number of openly genuine Nice Guys and Girls on one hand (that has several fingers missing). However, Davos Seaworth passes muster - a down-to-earth, moralistic smuggler-turned-knight who stands out among Stannis and his supporters for being able to relate amiably to nearly everyone from king to commoner.
Brienne of Tarth, who can be surly at times, but adheres to a high code of honor and is very compassionate, also passes. However this is debatable considering her unpleasant behavior towards Davos, treating him as untrustworthy on very flimsy grounds, and her taking obvious glee in murdering Stannis, even mocking his former retainers about it. This is a departure from the much kinder and less violent Brienne from the books.
There's also Gendry, an unambiguously heroic person.
Most of the Stark family, be it Ned, Robb, Bran, or Jon Snow. Ned is shown to be greatly respected and admired by the smallfolk under his care, many of whom are still loyal to the Starks, long after most of them have been wiped out. He was so nice that he even tried to protect Cersei's children, despite them being incest born and their family being enemies to the Starks. Ned is easily one of the most honorable characters in the series. Robb is an overall warm, righteous and compassionate man, rare traits for the leaders of The War of the Five Kings. Jon is definitely a Stark in all but name and is widely considered one of the most compassionate and moral characters in the Crapsack World that is Westeros, though not without his prideful moments. Bran is following the footsteps of Robb, Jon, and his father in terms of how nice he is.
Jon's best friend Samwell Tarly also qualifies. He never so much as raises his voice to another character until he really wants Pyp to open the fucking gate in "Watchers on the Wall," which Pyp immediately lampshades.
Pyp: "I never heard you curse before."
Most of the (living) characters in Daenerys Targaryen's court are pretty damned decent and friendly people, which should indicate the kind of leader Daenerys is (though she's not above some brutal retaliation against her enemies, she has this for her default setting, making her one of the nicer characters in the series) and treats her household almost like family. Even Daario Naharis mellows out a lot, and Tyrion settles into full hero protagonist mode (after previously being an anti-hero) once he enters her service. Ser Barristan Selmy is an upstanding knight who proves polite enough to give the accused spy Jorah a heads-up before informing his queen about the pardon from King Robert.
Talisa is an all-round pleasant, if snarky, person who has a very low opinion of warfare, because of how it causes nothing but misery as she points out to Robb during their first meeting. Her altruistic need to help others is one of the reasons why Robb falls for her.
Pod is one of the few unambiguously good-hearted and loyal characters viewers meet in all of Westeros.
Fat Walda extends some sympathy toward Sansa for her predicament. However, Walda isn't particularly known for her ability to choose words carefully, so her attempts of sympathy still feel somewhat gloat-y, like reminding that Winterfell is not Sansa's home territory anymore.
While at first glance a Creepy Child, Jojen quickly shows himself to be a friendly and down to earth kid, if a bit mysterious thanks to also being a Psychic Child.
Meera is friendly, patient, and calm, though these tendencies are stretched a little thin around Osha.
Kevan Lannister is much more mild-mannered than his elder brother, though definitely not a pushover.
Myrcella Baratheon loves her uncle Tyrion and "uncle" Jaime, as well as her brother.
Tommen is a genuinely kind person who doesn't share Joffrey's sadistic streak whatsoever, and Tywin says that this temperament will make him a good king; at the very least, he can be counted on not to be Stupid Evil. This is presented as a questionable virtue for the King of Westeros, given he lacks the inherent ruthlessness needed to rule and nobody has any interest in Tommen developing a backbone.
A literal lifetime of slavery, senseless brutality, and combat training hasn't stopped Grey Worm from being cuddly.
Rakharo is the first well-meaning Dothraki shown in the series. He is friendly and personable by any standard, but especially when compared to the other Dothraki warriors.
Despite her disfiguration and spending her days hidden in her dark tower chambers, Shireen is a massive sweetheart who loves her father and Ser Davos dearly.
Lord Selwyn decided not to force Brienne into a life of political marriage, and helped her achieve her goal of becoming a knight, or as close thereto as a woman could manage.
Ted, the protagonist. Although he has his Jerkass moments like the rest of the characters, he's almost ridiculously hospitable and helpful towards his friends (to the point of once selling his new car to loan Marshall money after the latter loses his job, giving Barney and Robin scads of relationship advice despite the latter being his ex-girlfriend, and giving Marshall and Lily his own apartment as a baby shower gift, complete with a handmade crib, when he realizes they are miserable in the suburbs). He's also a hopeless romantic and sentimental sap, which is frequently highlighted by the show's penchant for gender-flipping tropes. One of the foremost examples: to dissuade her from having sex, he regales Robin's teenage sister with a story about how back in high school, he said "I love you too" to his girlfriend after she said she loved him to get in her pants, ran off the moment he finished banging her, and never called her back. He says that all teenage boys are like this, even the 'nice' ones like him. However, Ted later confesses that the roles were reversed — he was in love with the girl, who lied about being in love with him back to make him put out and never called him back.
Ted's best friend Marshall is pretty much the poster-child for this trope. He's sweet, sensitive, innocent, good-natured, idealistic, romantic, and can't bear to hurt anyone (which is why it's such a shock when he beats a guy unconscious in retaliation for punching Ted). Also puts him into Gentle Giant territory given that Jason Segel is about 6'4.
Dangerous Davies from The Last Detective. If it wasn't based on a novel series and previously played 30 years ago in a one shot film by Bernard Cribbins, it wouldn't be farfetched to think that this role was created exclusively with Peter Davison in mind. D.C. Davies is called Dangerous because he's anything but. He's called the Last Detective because he's the last one anyone thinks of to send on an important case. He's honest, fair, non-assertive, and generous. These are the sort of things that apparently make a bad cop. This is true since all the other coppers are portrayed as cynical, hardened, insensitive, and borderline corrupt.
Miss Brooks is a nice girl example, who is always trying to help others (and marry Mr. Boynton). Mr. Boynton is also a nice guy, unfortunately for Miss Brooks, he's Oblivious to Love. Miss Brooks finally marries him in the Grand Finale.
Mrs. Davis, Miss Brooks' landlady, is a second nice girl example.
Harriet Conklin also counts as a nice girl example. Her father, scheming and domineering Principal Osgood Conklin, is definitely not a nice guy. Walter Denton may be nice overall, but is too much of a prank player and troublemaker.
Power Rangers. If you're going to be the Red Ranger, it's practically mandatory that you're one of these.
T.J.'s moment in Turbo came when he helped Bulk and Skull out of a predicament where they were being blamed for some packages disappearing, going on a stakeout with them and even helping set a trap for Divatox's minions when the Rangers found out she was behind the thefts. The whole time, T.J.'s just as concerned with clearing Bulk and Skull's names as he is with foiling the bad guys' plans.
Early on in Time Force, Wes's limo is struck by a stray baseball. Wes gets out and tosses the ball back to the child who threw it with a smile and without saying a word. He also buys contemporary clothes for the rest of Time Force and helps them get acclimated to the 21st century.
In an early episode of Power Rangers Megaforce, Troy doesn't hesitate to come to the aid of a younger student who's being bullied.
Press Gang: Kenny is depicted as this by Lynda and by the girl from Dublin. He's pretty insulted by Lynda by saying he's nice to everyone.
The "well-balanced" part doesn't apply (in fact, he has myriad issues), but otherwise Ned from Pushing Daisies fits this pretty well. He may be a bit aloof, but he's just shy, not rude, and he's sincere, kind and principled.
Quantum Leap: Sam Beckett. He's not quite an All-Loving Hero, but he's friendly, never takes advantage of women, and well, the fact of the matter is he always wants to help people he's around, even when they annoy him.
Schitt's Creek has a number of nice guy characters who are not push overs or wimps:
Johnny Rose adores taking care of his wife Moira and puts up with a great deal of melodrama from her, but he also will stand up to her and call her out when necessary. He loved making her happy with lavish gifts, and he feels bad he can no longer afford them but Moira remains devoted to him despite his loss of wealth. They have been Happily Married for almost 40 years.
Initially portrayed as a weak nice guy, Ted develops a backbone after getting dumped twice by Alexis. He also develops a six-pack through his post-breakup workouts, and Alexis realizes her mistake. They become a happy couple after she works hard on herself to become worthy of him.
Patrick is the first nice guy David has ever dated, and David loves him all the more for it. Like Johnny to Moira, Patrick loves taking care of David and is attracted to his creativity and flamboyance, but he also will stand up to David and won't let David push him around.
Even after they break up, Mutt and Alexis manage to stay friendly. Mutt also invites his romantic rival Ted to his barn party after both of them have broken up with Alexis.
Travel blogger Emir Kaplan is portrayed as kind and understanding of Stevie and her friends' foibles, ethical in how he conducts his reviews and upset with himself for nearly standing her up.
Kes of Star Trek: Voyager is possibly one of the nicest people in the whole franchise. She's sweet, understanding, kind but not spineless, advocating for the Doctor and wanting to learn as much as she could about the universe during her nine-year lifespan.
Sam is the perfect example of a Nice Guy. This really pisses him off because everyone keeps taking advantage of his nature. Then we discover his origins and he's still a nice guy after that, despite his Dark and Troubled Past. He does have vague stalkerish tendencies and dates his employees.
Major Healey from I Dream of Jeannie is made of this trope. He treats Jeannie a lot better than Major Nelson does, and is always going out of his way to support and cheer on the other characters.
Most of the other characters are unfailingly polite and fit into this trope. The older male authority figures are stern but very polite and supportive (especially considering all the hijinks that the Majors and Jeannie pull, and are surprisingly forgiving and fair (if somewhat by-the-book). When the psychologist found out that Major Nelson was being investigated as a tax cheat, he was quick to defend him. And Major Nelson might be somewhat uptight and exasperated by all of Jeannie's stunts, but he clearly cares a lot about her, too, and will often go out of his way to do nice things for her and Major Healey.
While most people in Taxi are generally very kind, Reverend Jim Ignatowski stands out. Anyone that considers Louie not only as a friend, but a hero, is enough justification for him to fit in this trope. And that's just the beginning.
Zena Sherman, Louie's girlfriend qualifies by just being "Louie's girlfriend" regarding his personal problems. In spite of breaking up with him in the third season premiere, she wanted to be friends with Louie, though it's clear that he would never accept that.
Lister and Kryten from Red Dwarf both fit this trope, although Lister is quite good at standing up for himself against Rimmer or Cat, wheras Kryten has some programming to overcome in order to find a backbone.
Xander. A friend to pretty much everyone who is not a vampire, his Undying Loyalty is pretty much a superpower to someone who is just a Badass Normal in a World of Badass. Indeed, he was The Heart to a spell to possess Buffy, and had this trait in the series as a whole, trying to reach out to any human person in their time of need, even Faith after she kills someone and shows no remorse for pinning the blame on Buffy.
Riley gets something of a Deconstruction early on - he was a prime example of how to not do this character since he ended up being regarded as a bland Replacement Scrappy for Angel (and later attempts to make him more compelling as a Love Interest for Buffy worked.). However, Riley comes back to the show Happily Married and his nice guy persona is much better executed. When he finds Buffy working in a dead-end job and sleeping with Spike, Riley refuses to condemn her for it, instead giving Buffy the encouragement to start pulling her life back together. His wife, Sam, is really really nice and supportive, even when Buffy kills a demon they were tracking.
Tara McClay is most definitely one of the nicest people in the series and — after overcoming her Shrinking Violet phase — she proves to be the most morally well-adjusted of the main cast, dispensing advice to the others on coping with grief after Joyce died. She's also a very understanding and forgiving (without being a doormat about it) lover to Willow, and becomes the group's Cool Big Sis and Team Mom (especially to Dawn).
Principle Flutie; he was well-meaning, but bumbling. Still, he gave Buffy a fair shake, which is more than can be said for most Sunnydale adults who aren't an English librarian.
Detective Dowling in the comics. He clears Buffy's name, then has Spike show him the world of vampires; Spike takes a liking to him and when asked about Buffy suggests she should be with him. After he tries to take on a vampire nest and is abandoned Buffy does seek him out, but thinks she has nothing to apologize for and his willingness to be Just Friends is enough to upset Spike and Willow over his Angst? What Angst?.
Clem is easily one of the friendliest characters in the series.
In Noah's Arc, Junito is probably the best example, being consistently kind, courteous, patient and understanding with Ricky (who is a promiscuous, emotionally stunted, and often times Jerkass individual).
Despite the fact that that the town of Deadwood is mainly comprised of drunks, slime balls, gamblers, thieves, and murders it has its fair share of nice guys. Chief amount them being Sol Star who manages to be nice to just about everyone in the camp (no easy feat) and to be Heterosexual Life-Partners with the perpetually short tempered Seth Bullock. Other nice guys include Ellsworth, Blazanov, Merrick and Reverend Smith
Dr. Archibald Hopper. He's capable of being civil and helpful to just about anyone. Just don't ask this amnesiac cricket to ignore his conscience or you'll get an earful.
Belle. She seems to be the only person in both worlds who is genuinely nice to Gold, and she goes out of her way to help Grumpy realize that he's in love with a fairy while she's still trying to deal with having her heart broken. Not to mention, she's willing to work with Hook and Regina despite the fact the two have kidnapped, threatened, and generally abused her (though she does call them out on it first).
Prince Charming/David Nolan. He's pretty much Captain America, being a humble, friendly and down-to-earth guy who's also a total badass and The Leader when there's need for one. He did cheat on his wife and cause a great deal of stress to both her and the woman he loves, but that was due to trying to be good in-spite of the effects of the curse.
Bob Ross, host of The Joy of Painting, was well-known for his soft voice and calm, gentle demeanor.
Stargate SG-1 has Doctor Daniel Jackson. He's the moral center of the group, eager to learn about alien cultures and try to see things from their perspective, always advocating for finding a non-violent solution and genuinely being a great friend and good person. Beware the Nice Ones, though, because, even before he Took A Level In Bad Ass, he wasn't afraid to show the Goa'uld just how personal the whole thing was for him. Of particular note is the first season episode where he considers killing a vat full of larval Goa'uld symbiotes but Carter dissuades him with an If You Kill Him, You Will Be Just Like Him speech. He appears to accept this, only to come back and machine gun the container, killing all of the baby Goa'uld.
While all the cast from JAG would qualify, Bud Roberts stands out from the rest as an all-around nice and humble guy.
From Merlin: Merlin, Guinevere, Freya, Lancelot and Mithian are all genuinely nice, sweet-natured people. (Though Merlin grows darker as the series goes on and becomes more and more liable to throw people under the bus in order to preserve his personal vision of the future).
Midshipman Clayton was very nice when he took care of sea-sick Horatio who threw up as he came aboard Justinian, tucking him in a hammock. Later he would bring him a Spot of Tea, or a Spot of Grog, actually, when Horatio had a watch or some responsibilities on deck in the rain. Clayton suffers a fate of many a Mr Nice Guy by becoming... Mr Dead Guy. He fought in Hornblower's stead in Duel to the Death when he felt shamed by Hornblower's bold challenge.
Mariette in "The Frogs and the Lobsters" was such a Nice Girl. She would always hold or cuddle a child to emphasise how sweet and nice she was. How else should viewers know?
Stuart is the only genuinely nice main character on the show.
In Six Feet Under, Claire Fisher dates a nice boy Toby. Claire and Toby promptly break up when he criticizes Claire's attitude. He thinks she's too cynical and mistaken in believing that her life sucks. Lampshaded when Claire's brother's girlfriend Brenda comments how nice he is (and how he differs from her usual boyfriend type of Troubled, but Cute).
Brenda: Toby seems nice.
Claire:[sarcastic] Yes, Toby is very nice.
Brenda: Not your type, huh?
Claire: A deranged psychopath? No, I guess he's not.
In Glee, Marley Rose is unfailingly nice to just about everyone she meets, even when those people have blatantly insulted her and willingly talked her into an eating disorder out of spite. She does, however, have a breaking point. The girl who stole her boyfriend gets treated with liberal doses of deadpan snark.
Sam Evans is also one of the genuinely nicest guys in the show, particular in Seasons 2 & 3.
Steve Urkel of Family Matters is a klutzy, awkward, annoying nerd who can never take a hint that he isn't wanted around (which he never is). In spite of all of that, he's one of the most genuinely kind, caring, positive, and unflappable people in the world, and would do anything for the Winslow family.
Barry Allen is empathetic and friendly for the most part, and will protect his friends and strangers alike. However, that doesn't mean you should cross him.
The real Earth-1 Harrison Wells was very kind. He wanted to create a government-free laboratory that helped all mankind. Then Eobard Thawne steals his identity.
H.R. Wells is annoying to the team, but he never takes offense at the team's insults, is always pleasant to them and even offers to mentor Wally West.
Walter Steele from Arrow to an almost comical degree. He is polite and gentlemanly to everyone. It's almost as though he doesn't realize he's in a Darker and Edgier version of the DCU.
Felicity Smoak. One of her defining traits is her kind, empathetic nature. Shes often seen giving advice to many of the heroes of the Arrowverse including Oliver, Barry, Cisco, Laurel, John Diggle and other characters.
John Diggle. While stoic and a bit on the snarky side, hes one of the most righteous and moral characters in the show. He never fails to be polite, honorable, loyal, and compassionate towards his friends and allies.
Eric Foreman from That '70s Show is a genuinely sweet and nice guy, it's even lampshaded in one episode how he's the only one out of his group of friends to have some kind of moral core. He's even nice to people he doesn't necessarily like when they need his help, such as Jackie when she thinks she's pregnant and Laurie when Red all but disowns her.
Steve Jinks of Warehouse 13 is a genuinely kind, good natured man who very quickly slots into the family dynamic of the show. He's barely on the show for two episodes before he and Claudia become inseparable to the point where he essentially becomes her substitute big brother.
Fabian is kind to the point of being an Extreme Doormat. He is always the one to feel bad for someone being hurt and tries his hardest not to make anyone get hurt. He gets sarcastic and angry at times, but is always a good friend and puts others before himself constantly.
Mick, the series' Lovable Jock. He does have an aggressive streak, but has proven to be a sweet guy who really does care for others deep down. He's also good-natured and supportive, if oblivious at times.
Willow is possibly the nicest person in the house. She's very empathetic and though she's a Cloud Cuckoo Lander, she does pay attention to when people are hurting and tries to help them. She loves animals as well and even tried to make Victor happy.
Trudy, too. She's a very motherly and sweet person who takes care of everyone in the House and genuinely tries to help them when she can. She defends them from Victor as well.
Fitz, probably moreso than Coulson. Besides the time he became a resentful and snappy while recovering from brain damage, he's typically an unassuming, nerdy, submissive, surrogate younger brother to the team.
The titular heroine in Supergirl is a thoroughly sweet natured and helpful person.
When her more famous cousin shows up in Season 2, he's every bit the easygoing and noble hero you expect him to be, and a Cool Big Bro to Kara from the get go.
Agent Olympia from Odd Squad is portrayed as this in Season 2. She's generally a sweet, kind-hearted agent who's devoted to her work, and her co-workers, including Agent Otis.
Wonder Woman: Steve Trevor in spades. War hero (constantly referred as such in season 1). Fighter jock ("The New, Original Wonder Woman", "The Feminum Mystique", and others). Rose Bowl (presumably winning) quarterback ("Fausta, the Nazi Wonder Woman"). Tall, handsome, gleaming smile (literally true in the opening credits of season 1), and will sacrifice his entire career and risk his life for Wonder Woman without hesitation ("Fausta, the Nazi Wonder Woman").