Signer Dragon

The Five Dragons are a series of Dragon-Type Synchro Monsters, introduced in Yu-Gi-Oh! 5D's. These legendary dragons play a part in the legend of the Crimson Dragon, as well as being connected to the Signers themselves. That connection being that these legendary beasts who are actually servants to the Crimson Dragon, were the ones who sealed an evilness within the Nazca Lines.

That same evil, which is now known as the Earthbound Gods, has reappeared once again in the world as Duel Monsters cards used by the Dark Signers.

So far 4 of the Five Dragons have been released in the OCG and TCG: "Stardust Dragon", "Red Dragon Archfiend", "Black Rose Dragon" and "Ancient Fairy Dragon". The supposed mechanical version of the fifth dragon, Power Tool Dragon, was released in Raging Battle in the OCG.

In the anime, Professor Fudo gave the "Stardust Dragon", "Red Dragon Archfiend" and "Black Rose Dragon" Duel Monsters cards to Rex Goodwin. As these three, along with the "Ancient Fairy Dragon" card were originally designed so that their corresponding Signer could activate the safety switches for the Old Enerdy system.

Members
Each of the five Signers possesses one of the Five Dragons. Currently, all five dragons have been shown and associated with a Signer, although only four have been named:

"Power Tool Dragon", which belongs to Leo, looks like a mechanized version of the fifth Dragon, resulting in Leo believing he is the fifth Signer. Luna tells him it's possible that Power Tool Dragon fought alongside the Five Dragons in the ancient war between the Dragons and the Earthbound Immortals, but she only does so so as not to sadden him, as a mechanical dragon could not have existed in ancient times.

Assault Modes
"Stardust Dragon" and "Red Dragon Archfiend" have their own "/Assault Modes": "Red Dragon Archfiend/Assault Mode" and "Stardust Dragon/Assault Mode". Both of them were Summoned by Yusei and Jack in a special episode.

Summoning Quotes
In the Japanese anime, when Synchro Summoning one of the Five Dragons, their corresponding Signers chant a quote that describes them.

Yusei Fudo
''Tsudoishi negai ga, arata ni kagayaku hoshi to naru! Hikari sasu michi to nare! Shinkuro Shoukan! Hishouseyo, Sutādasuto Doragon!!! "Clustering hopes become a new shining star! Become the path its light shines upon! Synchro Summon! Take flight! Stardust Dragon!"

Jack Atlas
''Ouja no kodou, ima koko ni retsu wo nasu! Tenchi meidou no chikara wo miru ga ii! Shinkuro shoukan, waga tamashii, Reddo Daemonsu Doragon!''

"The ruler's heartbeats will now fly through here! Take witness to its creation-shaking power! Synchro Summon! My very soul! Red Demons Dragon!"

When Jack summoned Stardust Dragon in his duel against Yusei in episode 4 he chanted "Behold the wings guided by the great winds! Synchro Summon! Reverberate. Stardust Dragon!"

Aki Izayoi (Akiza Izinski)
''Tsumetai no honoo ga sekai no subete wo tsutsumikomu! Shikkoku no hana wo hirake! Shinkuro shoukan, araware yo, Burakku Rouzu Doragon!''

"Chilling flames engulf the entire world! Pitch-dark flower, set into bloom! Synchro Summon! Appear now! Black Rose Dragon!"