Angel: Doyle's porkpie hat, similar to the one worn by Whistler in Season 2 of BtVS (on whose character Doyle is based).
The Tudors displays quite a fantastic plethora of Nice Hats, most notably those worn by King Francis I and Charles Brandon. The good people of England never complained about Henry VIII creating his own church because they were too Distracted by the Sexy.
In Merlin, the official servant's ceremonial clothes include a huge feathered monstrosity of a hat. Gwen even comments, "nice hat," in between giggles.
Johnny Carson's shtick as Carnac the Magnificent was well known for the giant turban that apparently granted him psychic powers.
On the A&E TV series A Nero Wolfe Mystery, Archie Goodwin (Timothy Hutton) always dressed very well whenever he went out on business or pleasure, frequently topping off his outfit with a snappy fedora. Wolfe himself (Maury Chaykin) sported a few Nice Hats of his own on the rare occasions when he left the brownstone.
There's also Badger, who, despite being a villain with a questionable taste in ties and suits and sports a bare chest under his coat and vest, wears a nice little derby, referred to by Mal as a "very fine hat".
Also, an inversion, where a Nice Hat doesn't help:
Mal: That's a mighty fine gun. Gun like that, boy must be your best shooter. Patience: We call him Two-Fry. He always makes it quick and clean. Mal: Two-Fry. Nice hat. (Jayne's sniper shot puts an entry hole in Two-Fry's hat, and his head)
Even Mal aspires to Nice Hat-dom with these comments:
"And I'd like to be king of all Londinium and wear a shiny hat."
"I swear by my pretty floral bonnet I will end you."
Saffron: I thought last night during the ceremony that you were pleased. Mal: Well, yeah, last night I was. Had some mulled wine, pretty girl gave me a hat made out of a tree◊. Nobody said I was signing up to have and to hold.
It is worth noting that the vast majority of characters on the show who wear hats are bad guys. Joss Whedon half-jokingly said it was how you could always tell who the bad guys were. They always had hats.
Benton Fraser's Mountie standard issue wide-awake hat in Due South, which has a brim stiff enough to knock someone out when hurled Frisbee-style.
Some fans point out that Fraser's susceptibility to injury and harm is dependent on whether or not he has his hat. If he has his hat, he is invincible (the hat once saves him from being shot at point-blank range, by taking the bullet no less). The bullet went straight through the hat front-and-back, but without the hat, he'd spend an episode in the hospital. Inversely, through the entire episode of Victoria's Secret, he almost never wears the hat, and ends up accidentally being shot and wounded by his partner.
Not one to be outdone in the fashion department, Romana sported at least four (if you count "Shada"). Not counting the awful Burberry one from "The Stones of Blood" that today screams uncool, there's "The Androids of Tara", "City of Death" (topping off a rather memorable outfit), "Shada" and the time she wore the entire Fourth Doctor get-up.
Though they're all tame compared to what most Time Lords wear.
The Second Doctor was somewhat prone to hat envy: "I should like a hat like that."
The Third also tried on a flat cap in his first appearance, before settling on a fedora. In his other installments, he went bare-headed.
Susan was also spotted sometimes wearing a fetching '60's style cap.
Eleven has a fondness for hats which, combined with his rampant Attention Deficit... Ooh, Shiny!, often results in him acquiring a new one in the middle of saving the world. In "The Big Bang", he picks up a fez out of a museum, claiming that "Fezzes are cool". Amy and River take initiative to stop him from adding this to his accoutrements (which already contains a bowtie) by snatching it off his head, throwing it into the air, and blowing it up. The fez has now reached Memetic Mutation levels, both in the show and fandom. It has become the Doctor's ongoing battle to try and keep a fez. He even steals one from Einstein. In the first episode of Series 6, he turns up in America wearing a Stetson (which makes additional appearances later on), only to have River Song shoot it off his head. Top hats, a pirate captain hat and a bowler hat have also made their way onto his head.
The Seventh Doctor was the first to indulge in fezzes, briefly swapping out his usual hat for one episode.
The Tenth Doctor briefly sported a fez in the 50th anniversary special.
During the Fourth Doctor's time, we were introduced to the White Guardian and the Black Guardian, who wore surprisingly tasteful headgear made from birds. (A white dove and a black raven, presumably.)
On Star Trek: The Next Generation, Whoopi Goldberg's character Guinan often wore what looked like a card table draped with velvet on her head. Behind the scenes, these hats were chosen because they hid Whoopi Goldberg's dreadlocks, which they thought wouldn't look right on Guinan (in later episodes, however, we end up seeing her dreadlocks anyway). She also had a hexagonal version.
Spoofed in Sev Trek: Pus in Boots where Guinan's hat is used as a tray for serving drinks in Ten Forward, then as Weaponized Headgear against a rampaging alien shapeshifter.
In Star Trek: Deep Space Nine, Worf first meets Kira and Dax as they're exiting the Holosuite in ridiculous medieval regalia, complete with huge garish headgear. Worf's only response: "Nice hat."
Apparently Deep Space Nine actually had a specific part of their budget allocated toward making hats for various Planet of Hats aliens. Unfortunately the camera operators kept complaining the hats were obscuring the actors' faces, so the idea was dropped.
There's also Kai Winn's omnipresent little yellow hat◊. It was a lot neater than the ridiculous headgear she had to wear as a mere Vedek that looked like the Sydney Opera House.
Spock would frequently wear hats when visiting human planets incognito on the original Star Trek. Ostensibly to cover his ears and eyebrows so he could pass for human, according to many sources it was really so Leonard Nimoy didn't have to wear the ear pieces, which made his ears very sore by the end of each season.
Michael Garibaldi on Babylon 5 had a film-noir style fedora that he would occasionally wear for doing detectiv-y things. When G'kar leaves the station to search for him, he takes (and wears) the hat.
Played with in The Mighty Boosh episode "Electro." Howard meets the Spirit of Jazz, an intimidating ghost with a white top hat that's always on fire. At the end of the scene, the Spirit freaks out because he didn't realize that his hat was on fire. Howard apologizes for not warning him, saying he thought it was "just his look."
The Hitcher also wears a rather nice top hat, with polo mints imbedded into the band.
It should be noted, however, that everyone who isn't the eponymous Kolchak thinks the hat's ratty and ugly. Ms. Emily tried to get him to wear a genuinely nice (if unsuited to him) cowboy hat. It...didn't take.
In one episode of Michael Palin's New Europe, he wears a huge hat made of oak leaves whilst celebrating a Latvian midsummer festival at which it's traditional for men to dance wearing one.
When Cain escapes from the Longcoats in Tin Man, he takes the time to wreak a little extra vengeance on the one who stole his hat.
In the Canadian children's show Today's Special, the main character, Jeff, is a mannequin brought to life by his magic hat (cap, really). When he takes it off, or it comes off, he turns back into a mannequin.
The Buffy the Vampire Slayer episode where she has the flu and is languishing in the hospital as Das Kindestod stalks the hall of the children's wing. It wears a Nice Hat, and when she brawls with it, the hat comes off. He seems to defeat her, picks the hat back up, and — this is the key point — makes sure the brim is straightened as he stalks off.
Frank from 30 Rock has a collection of humorous trucker hats, a variation on the Fun T-Shirt.
Angel Batista from Dexter usually sports a very sharp-looking hat.
Steed from The Avengers always wears an impeccable bowler hat, as befits his status as a perfect English gentleman. The steel plate concealed in the crown is just a bonus.
You will see Jamie Hyneman of MythBusters without his beret only while he is in the middle of putting on diving equipment or fireproof suits, and even then he will not been wearing it only for as long as absolutely neccessary.
Meanwhile, his co-host Adam Savage will put just about anything on his head.
He does wear a nice, brown Indiana Jones number pretty regularly.
The first season of Ghost Whisperer had a recurring evil spirit best-known as "Wide-Brim" after his distinctive, and yes, very nice hat.
Fruit from The Wire; in fact his pimp hat is a necessary distinguishing feature to get the audience to recognize him among the huge influx of new drug dealer characters in season three.
Also, in Season 1, Bubbles used a bag of Hats as a way of marking drug dealers for the watching police and their cameras. He had a particular red Nice Hat that he only put on major players.
A recent episode of The Daily Show featured the Secretary of the Interior giving Jon Stewart an exceedingly nice cowboy hat, matching the one the Secretary was already sporting.
Sister Bertrille was known as The Flying Nun because her hat was so nice it let her fly.
Jeeves and Wooster actually lets us see the hats that were only described in the original novels and that have driven so many plots with the arousal of Jeeves' Ultimate Fashion Police ire: The Alpine, the 42nd Street skimmer, the 10-gallon...
Battlestar Galactica. While on New Caprica, Brother Cavil wears a hat that gives him a suitably sinister look, especially when he's arranging for the arrest and execution of several hundred hostages.
In Homicide: Life on the Street, Detective Lewis is rarely seen outside of the station house without his cool trilby. Detective Pembleton is also at times given to wearing a pretty sweet fedora. Various other rather cool hats make their appearance throughout the show.
Played with in the latter half of season three, wherein Bolander frequently wears a trilby... because he's been recently shot in the head and wears it to conceal the horrific scars.
1975's The Ghost Busters was pretty much all about the nice hats. Tracy, the gorilla sidekick, would go through about 10 hat-changes or more through the course of each episode.
In the pilot episode of White Collar, Agent Burke's probationary agent compliments Neal Caffrey on his hat when she first meets him, leading Caffrey to think that she's flirting with him, when Burke tells Caffrey that "She'd rather be wearing the hat", implying that she's actually a lesbian (which is confirmed later in the episode).
Sharp-Dressed Man Neal has continued to wear the fedora, much to Peter's annoyance. In one episode, a witness for a case starts fanboying over Neal and gets a fedora of his own. He even changes his online dating profile picture to include the hat, which later allows Neal to take his place on a blind date with a suspect.
Since he keeps his gut-pouch covered, the only thing preventing Teal'c from passing for human is his gold forehead tattoo. The obvious solution is a selection of Nice Hats, or in one case a fake Afro and bandanna.
Meanwhile on the "Jayne Cobb's knitted hat" end of the trope, we have the absurd headdress◊ worn by the minor Goa'uld Zipacna in "Pretense".
Leverage: If Nate Ford (also played by Timothy Hutton) can wear a hat, he will. And he looks damn good doing it.
Shotaro Hidari, the eponymous Kamen Rider Double, has a whole collection of Cool Hats he took up upon the death of his mentor, Sokichi Narumi. The Movie shows that Shokichi wore his Cool Hat before and after transforming into Kamen Rider Skull, a trait retained when the Dummy Dopant impersonates him. The way to tell the real Skull apart from the Dummy impersonating him is that the real Skull's hat has a notch in the brim, gained when one of the Taboo Dopant's energy bombs nicked it.
Worth pointing out, out of all Sokichi's hats, the only one Shotaro never touches is the white hat he was wearing when he died. In the penultimate episode, he finally takes that hat off the wall, signifying to one and all that the time for silliness has ended.And then he uses it in the fight where he kicks the Utopia Dopant's ass. Without transforming into Double.
Princess Ariel and her handmaiden Cassandra sport some pretty spectacular headdresses on Wizards And Warriors. Evil Wizard Vector claimed not to wear a hat - which means he had very odd hair.
Abby Bartlet, The West Wing's First Lady, occasionally wore scary wide-brimmed cartwheel hats, mostly for solemn occasions like funerals.
Scrubs: The rather outlandish hat that Turk wore after becoming Chief of Surgery probably qualifies. The fact that it was made by The Janitor probably nets it some sort of bonus points.
Justified: Deputy Marshall Raylan Givens is usually seen with his large beige cowboy hat.
Oz: Adebisi always wore a small knit cap perched on the top of his head. One of the other characters once asked him how he got it to stay there.
The America's Got Talent contestant Hannibal Means' actual performance is based on his singing, which is excellent, but he is also remembered for his unusual dressing habits, one of the most memorable of which featured a hat shaped like a rooster. More than that, he actually crochets these hats, and got Nick Cannon to wear one (which probably wasn't hard) during his most recent performance.
Farscape: When Crichton said that War Minister Ahkna scares him, Claudia Black ad-libbed the line "It's the hat."
Vince Noir from The Mighty Boosh sports a wide array of awesome hats throughout the series. In one episode Howard curses Vince that the next hat he tries on will not suit him, prompting Vince to say that "All hats suit me! My hair is virtually a hat!"
Hee Haw: Minnie Pearl's flowery straw hat with the price tag hanging from it. She was apparently mortified after her first appearance with it, when she realized she'd been in such a hurry to dress that she forgot to remove the tag. But the audience thought it was hilarious, so she kept it after that.
Bobby Singer on Supernatural is almost never seen without his trucker cap.
In an earlier episode, Xena had let herself be arrested by a corrupt ruler, in order to contact a rebel leader who was already in prison. Gabrielle, wearing what looked like a bowler, later arranged to get arrested as well, in order to smuggle in Xena's chakram (which was disguised as the brim of her hat), as well as her whip (which Gabrielle wore around her waist like a belt).
Also from The Monkees, the beginning of the episode Captain Crocodile saw the series' protagonists having cute little leafy green bathing caps put on them (albeit to keep cream out of their hair when they each subsequently received a Pie in the Face). These same caps were worn by the members of the band The Jolly Green Giants in the earlier Find the Monkees story.
The Shadow Line has Gatehouse, who wears a nice trilby in most of his appearances.
Star-burns on Community acquires one for the second season.
Walter White from Breaking Bad wears a black porkpie when in his Heisenberg persona.
Cowboys Jet & Cord from Seasons 16 & 18 of The Amazing Race would never be seen without their cowboy hats, and always kept them on, even while bungee jumping. On the final leg of Season 16, Jet's character avatar at the Industrial Light & Magic challenge was even given a cowboy hat.
When the Rangers from the future in Power Rangers Time Force get 21st-century clothing, Wes gives Trip a bucket hat to top off his ensemble (and to disguise the fact that he's a Human Alien by obscuring the crystal in his forehead.)
Wes: I don't know if the public is quite ready for a Xybrian yet.
Being set in a medieval-style world, Game of Thrones is as full of Nice Hats as it is full of Chronic Backstabbing Disorder. A special prize should be awarded to King Renly Baratheon, who wears a fancy, golden crown shaped like stag antlers. It's arguably the most striking piece of headwear in the series.
In universe, Sherlock's hat becomes this, much to his dismay.