Flaming Skulls

Drive-Thru Whale: "Would you like flaming skulls with that?"

Strong Bad: "Do you have to ask?"

—Strong Bads Cool Game for Attractive People Episode 2: Strong Badia the Free

Skulls are cool. Fire is cool. This is what happens when the two have a baby in your brain.

Compare Crystal Skull.

Examples of Flaming Skulls include:

Anime and Manga

In Tengen Toppa Gurren Lagann, the logo of Team Gurren is a flaming skull with Cool Shades, bearing no small resemblance to the Gurren itself. At the end of the series, Gurren Lagann takes command of Arc Gurren Lagann takes command of Super Galactic Gurren Lagann takes command of Tengen Toppa Gurren Lagann, a Humongous Mecha the size of a galaxy, which is comprised entirely of giant flaming skulls.

Comic Books

Ghost Rider is made of this trope.
Blazing Skull was a Golden Age hero in the Marvel Universe. No prizes for guessing what his gimmick was.
Superman villain the Atomic Skull (the second one) in The DCU.
This is a favorite of Gina Diggers' father, making his head appear to be on fire, as a means of intimidating would-be suitors to his daughters. (He's an archmage. It's just an illusion.) He even calls it the "magical equivalent of polishing the shotgun."

Literature

In the Dream Park novel "The California Voodoo Game", one character uses a magic spell to make his head appear as a flaming skull in order to scare off a god.

Live Action TV

In the first ever Doctor Who story, the Doctor attempts convince the cavemen that he and his companions died by placing skulls inside a fire he started.

Music

The Exactly What It Says on the Tin symbol of punk band The Offspring, Fire skull.
Featured on the cover Oz's Fire in the Brain. On an unrelated note, that's Quorthon's hand.

Tabletop Games

Warhammer Fantasy traditionally has a Bright/Fire magic spell called "The Burning Head".
- Also: Screaming Skull Catapults. The ancient Khemri empire had a habit of keeping the heads of executed criminals, coating them in a special kind of pitch that not only burned well, but made a horrific screaming sound, and firing the things en masse at opposing armies via catapult. Coming back as a race of skeletal undead has not cured them of this habit.
  - There's an upgrade for the catapult that lets you fire the skulls of the specific race being fought at them. This hurts their morale rather badly.
Khornate daemons in Warhammer 40,000 are occsionally armed with the dreaded Burning Brass Skulls of Khorne. Presumably they kill people by being f*** ing metal.
- So who gets to wield the Burning Brass Balls of Khorne?
- Biker Nob Gutsmek once destroyed a Titan by ramping into it and killing everybody onboard. The crew's skulls, kept as trophies, are still on fire.
Dungeons & Dragons
- has a feat called "Spell Theatrics" that lets a caster change the visual effects of a spell. The example given is making a Fireball into a flaming skull.
  - There are several types of undead that also take this form.
- In adventure G3 Hall of the Fire Giant King, King Snurre's symbol is a flaming skull.
The Yu-Gi-Oh!! card game has a card actually called Burning Skull Head, as well as Skull Flame and Supersonic Skull Flame. Fittingly, Burning Skull Head and Skull Flame are FIRE-attribute Zombies (Supersonic Skull Flame is WIND instead).

Video Games

The Legend of Zelda series has Bubbles, flaming skulls which flutter around on little bat wings. Less awesome and more annoying in this case, as they seal Link's ability to draw his sword.
Lost Souls in the Doom series are pretty much Bubbles, only more lethal than annoying.
Clive Barker's Clive Barker's Undying by Clive Barker has a spell called Skull Storm which allows you to throw not merely flaming skulls, but flaming skulls that chatter with each other and explode upon impact.
Shang Tsung fires these as a projectile attack.
- And Scorpion has one for a head.
One of the early powerful Wizard spells in Puzzle Quest is called "Flaming Skulls".
An attack unique to the Grim Reaper enemies in Disgaea 3: Absence of Justice involves transporting the enemy into a Pocket Dimension, where they float down a large pillar and then are mobbed by burning skulls. This also qualifies for Nightmare Fuel.
In Strong Bads Cool Game for Attractive People Episode 2: Strong Badia the Free, the Drive-Thru Whale prompts Strong Bad to set a pile of papier-mache skulls on fire with the hint "would you like flaming skulls with that?" Strong Bad, being Strong Bad, replies "You have to ask?"
Prometheus from Mega Man ZX could summon 4 of these as one of his attacks.
One of the numerous varieties of Goddamned Bats of Terraria is one of these, and can usually be found in dungeon areas.
Variants of these appear as standard enemies in some dungeons throughout the Golden Sun series.
Flaming skulls are a destroyable hazard in Samurai Warriors 3 in its Murasame Castle Mode stages.
Castlevania: Symphony of the Night has large flaming skulls that serve as mid-level enemies.

Western Animation

Parodied in Foster's Home for Imaginary Friends when Bloo tells a ridiculous fantasy story, these are seen.
- And again in the episode "Mac Daddy", where Bloo insists they paint flaming skulls on the side of the soapbox racer and Cheese insists on bunnies. They compromise on flaming bunnies instead.