Spiky Hair

Spiky Hair is the process of using product to make the hair stand on end like spikes sticking out of the head. It's often associated with the punk rock subculture and in fiction, it's used to show that a character is wild and cool as well as being badass. While spiky hair is prominent in real life, fictional characters are almost always shown with perfectly spiked hair despite the fact that it would get flattened while they're in bed. While it is a typically male hairstyle, it has become somewhat fashionable for women to have a spiky hairstyle.

A perennial favorite of the Friendly Neighborhood Vampire. Why? No one knows. Maybe it reminds people of fangs.

Compare Anime Hair and Shonen Hair.

Examples of characters with Spiky Hair include:

Anime and Manga

Matt from Digimon Adventure. While many other characters sport wild and crazy hair, he's the only one who's actually stated to use gel.
Played with by Team Unicorn in Yu-Gi-Oh! 5D's, whose leader's hair has one long spike.

Comic Books

The Beano's Dennis the Menace and The Dandy's Smasher.
Calvin sports this, and even sports an Astro Boy cut in one strip.

Film

Rory O'Shea from Inside I'm Dancing and his bleached blond spikes. Not allowing him to gel his hair is one of the many ways the women in the care home try to restrict him.
The unnamed woman on the team from Alien vs. Predator has some truly amazing blonde spikes. They show how much of a badass she is though in an action movie the tough tomboyish girl doesn't last too long.
Freddie spikes his hair when he becomes a fan of punk music in School of Rock. Billy is also shown with spiked hair when they arrive at Battle of the Bands. Laurence also goes for this look during the performance.
Ryan Phillippe donned some impressive spikes for the film Homegrown.
The bully Rory Buck from Jack Frost 1998.
James Dean, Rebel Without a Cause.
Gary Oldman in Sid and Nancy.
Jonathan Lipnicki as little Ray Boyd in Jerry Maguire.

Literature

Nymphadora Tonks in the Harry Potter series favours her hair short, spiky and bright pink. Since she can change her appearance at will she obviously has no trouble spiking it up in the morning.
Lisbeth Solander from The Girl With the Dragon Tattoo is a goth girl with short spiky hair.
Mike from Twilight is said to have this hairstyle. The movies give him normal flat hair though.
- Alice Cullen is also said to have short spiky hair. In the movies her hair is a bit longer and a little less spiky.
Irish hero Slaine Mac Roth is known for his spiked back hair.
Jerry Cruncher in A Tale of Two Cities is described as having hair so spiky it would be dangerous to play leapfrog with him. His son has it, too.
Thalia Grace from Percy Jackson and The Olympians is described as a punk girl and has spiky black hair.

Live-Action TV

Spike from Buffy the Vampire Slayer is shown with spiky hair in a flashback to the 70s. And no, that's not where his name comes from.
Angel often wore his hair spiky. On entering the alternate dimension of Pylea the different supernatural rules allowed him to see his reflection and he reacted with distress, suggesting this is some horrible grooming accident created by his vampirism.
Both Chandler and Ross liked to have this hairstyle in Friends. Ironically Rachel told Ross he used too much gel when his hair was actually flat.
Vince from What I Like About You.
In S Club 7, Jon Lee adopted this style for the LA 7 season.
Abby Maitland in Primeval gave herself a short spiky style for season 3. She grew out her hair in season 4.
Leo's Evil Twin from the season 6 finale of Charmed.
June Tuesday on the short-lived That 80s Show
In "Forever RED (film)", Tommy Oliver has switched to this hairstyle, which is jarring to older viewers because previously he'd been a Badass Long Hair whose hair had lengthened with each passing season. It's still short and spiky when he returns as a regular cast member in Power Rangers Dino Thunder.
Banban "Ban" Akaza/DekaRed from Tokusou Sentai Dekaranger, though he grows it out from Mahou Sentai Magiranger VS Dekaranger onwards.
Ted in How I Met Your Mother, whose hair is almost fascinating in its intricately disheveled spikiness.

Music

As mentioned above, spiky hair is found in the punk rock subculture. It's often dyed various colours as well. Some schools aren't as strict about spiky hair as they are about certain other hairstyles, as long as the spikes aren't too severe.
Liberty spikes is a special style where the hair is grown long and spiked out, looking similar to the headdress on the Statue of Liberty where the name comes from.
Mark Hoppus, of Blink-182 fame.
Pretty much every member of Good Charlotte.
Derek Whibley aka Bizzy D from Sum 41.
Sid Vicious as mentioned above.

Professional Wrestling

Zack Ryder and his slogan "take care, spike your hair".
Indie wrestler Christina Von Eerie has her hair spiked up into a mohawk. Portia Perez once joked that it could be used as a weapon during matches.

Video Games

Because of Cloud Strife's outrageous hair, spiky hair is considered a trademark of Final Fantasy, even though it's a fairly uncommon sight in the series outside of Final Fantasy VII related stuff
Many characters from the Kingdom Hearts series have outrageously spiky hair, Sora and Axel in particular.
Hwoarang gets this hairstyle in Tekken 4 when he joins the army. It grows out between games.
- Jin Kazama and Kazuya Mishima.
Hwang Sung Kyung and his expy Hong Yun-Seong from Soul Calibur, despite the game being set in the 1500s.
Phoenix Wright from the Ace Attorney series. The rest of the cast frequently poke fun at him for it.
Crono from Chrono Trigger
The appropriately-named Spike from Ape Escape.
Sonic the Hedgehog, who has literally spiky hair in that he has quills.
In Fancy Pants Adventures, Fancy Pants Man, despite him being a stick figure, has three large spikes for hair.

Web Original

Cracked Photoplasty advertises a hair gel that makes the above video game examples possible in Ads for Products That Must Exist in Video Games.

Web Comics

Barry's hair from Newheimburg is gelled like this.

Western Animation

Bart Simpson of The Simpsons . Lisa and Maggie also count though they always refer to their hair as "points" instead of spikes.
- Also, Sideshow Bob, Bart's archnemesis, who actually resembles a palm tree.
Phil has this hairstyle in the first season of All Grown Up!. He has curtained hair in other seasons. Tommy also has really short spikes.
Phineas of Phineas and Ferb has this hairstyle.
Carver from The Weekenders has a combination of this and dreadlocks. Tino also gives himself this look when he's trying to impress a punk chick.
A DJ-lookalike seen in Tokyo Mater has large spoilers on his roof that resemble spiked hair.

Real Life

Harold Lloyd.
Victoria Beckham as well as her husband David both have had spiky hairstyles though not at the same time.
Freddie Ljunberg, when he still had hair, liked to dye it red and spike it up.
Guy Fieri of the Food Network and Diners, Drive-Ins and Dives has this as his most recognizable feature, and it's notable that even though he usually wears sunglasses he doesn't actually put them on the top of his head, presumably so as not to crush his hair, and instead puts them on the back of his neck.
This is actually becoming a trademark hairstyle for younger workers and college students in parts of Asia, to the point where those with 'spiked' hair outnumber those with traditionally slicked and parted 'dos in some contexts (though 'artificially unkempt' is catching on). Since many of them are from the generation that adopted it as a form of rebellion or due to Rule of Cool, the establishment has gradually become more tolerant. Still won't fly in high school or below, however.