Fire

Fire is a hazard that has appeared in various games, common amongst Fire themed stages where fire causes various hazards which Sonic has to overcome.

Fireballs
Sometimes lava pools will erupt balls of fire which, if the player is not careful with poor timed jumps, can get harmed by these fire balls. Often enemy robots or traps will shoot balls of fire at Sonic, such as certain cannons or gargoyles which shoot fireballs vertically.

Flamethrowers
Some enemies are able to spray fire. Whenever directly from a nozzle to attack or evenly all around themselves to defend.

Some enemies can magically control fire such as Fire Masters or the Dark Gaia Phoenix.

Lava
Molten lava is one of the most common hazards in fire themed stages which often take place in volcanoes. While it is possible to stand and run on lava, not without it causing harm, however it is possible to walk on lava with a Flame Shield granting crossing to various areas.

Power-ups
The Flame Shield is a reoccuring shield-based power-up which envelops the playing character in a sphere of fire and grants immunity from all fire and extreme-heat hazards.

Like the Thunder Shield, being submerged in water will loose the shield.

Other names variations of the shield are Red Shield (Sonic 3D Blast) and Heat Barrier (Shadow the Hedgehog).

Early games
Fire was first weaponised in Sonic the Hedgehog where Marble Zone is located on active volcanic lands and where lava pits spew fireballs or Fireball Cannons shoot fireballs at Sonic. The boss fight would be Dr. Eggman dropping fireballs on two stone platforms while Sonic had to avoid them over a lava pit in the middle.

Sonic Heroes
The Power Formation is assosiated with fire, such as the various Fire Combinations or attacks named after the word "Fire" with the power type members of the teams would often use.

Sonic and the Secret Rings
At the start of the story, Erazor Djinn strikes Sonic in the heart with the Flame of Judgment, a small fire that burns over Sonic's heart that once it eventually goes out, will kill Sonic.

In the game, Sonic can also collect Fire Souls to unlock features in the Party Mode.

Sonic Chronicles: The Dark Brotherhood
In Sonic Chronicles: The Dark Brotherhood, the game had an element system as common with most fantasy RPGs. Fire was one of its elements. Robots and Kron were resistant to fire while N'rrgal, Voxai, Zoah and other organic opponents are weak against it. Chao like Korus grants a fire shield while Pyraz grant fire damage to attacks.

Sonic Boom: Fire & Ice
In Sonic Boom: Fire & Ice, Team Sonic will have the ability to melt blocks of ice as well as other flamable elements. They will also have Ice to freeze and counteract the fire.

Blaze the Cat
Blaze is gifted with the power of pyrokinesis, which lets her create and manipulate fire in any way she pleases. Axel Jump being her standard jump where she pirouette and spins a funnel of fire around her. Her signiture boost is Fire Boost.

Iblis
Known as the Flames of Destruction, the Iblis is the raw, seperate power of the sun god Solaris and responsible for the destruction of Silver's future. It takes the form of a large monster made from magma.

Ifrit Golem
Regarded as "a djimm that controls fire", Erazor Djinn summons him to burn away the pages of the Arabian Nights. Sonic couldn't harm him due to being bound by the Flame of Judgment. However Sonic managed to weaken Ifrit Golem with the Water Blue World Ring and fought him.

Adventures of Sonic the Hedgehog
A Fireball Cannon appeared in the episode "The Last Resort" where Scratch and Grounder used it as a trap for Sonic but it failed and hit the volcano, which made a rock fall on them.

Sonic the Hedgehog (TV series)
A fireball was fired from a cannon in the episode "Sonic's Nightmare".