Game of Thrones: 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."
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.
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.
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.
A large part of the plot' is derived from the conflict between the moral greyness of the spy world and the relentlessly good-natured attitude of Chuck.
Chuck's friend, the aptly-named Captain Awesome is definitely a good-natured guy.
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.
Ross is Adorkable and romantic. He becomes a good father to his son Ben 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 goog 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 was emotionally abusive to 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.
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.
Sam is the perfect example of Nice Guy. This really piss him off because everyone keeps taking advantage of his nature. Then we discover his origins; he's a nice guy after that, despite his Dark and Troubled Past. He does have vague stalkerish tendencies and dates his employees.
Rory Williams of Doctor Who. A Nice Guy 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.
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.
Ted, the protagonist. Although he has his Jerk Ass 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.
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.
Though Riley gets something of a Deconstruction earlyon - he was 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.). Riley comes back to the show Happily Married. His wife, Sam, is really really nice and supportive, even when Buffy kills a demon they were tracking.
A female example is Tara McClay, most definitely - 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).
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 of Storybrooke, Maine. 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.
While we haven't seen much of her, Belle is shaping up to be the female version of this trope. 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.
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?
Howard became a Nice Guy, inexplicably, once he start dating Bernadette.
In Six Feet Under, Claire Fisher dates a nice boy Toby. Caire and Toby promptly break up when he criticizes Claire's attitude. He thinks she's too cynical and mistaken in believeing 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.