From Yu-Gi-Oh!

The Signer 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 Immortals, reappeared once again in the world as Duel Monsters cards used by the Dark Signers.

The 4 of this Dragons have been released in the OCG/TCG which are: "Stardust Dragon", "Red Dragon Archfiend", "Black Rose Dragon","Ancient Fairy Dragon". As for "Blackfeather Dragon". is it known to released this month.

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 Ener-D system.

Four of the dragons has at least one special support card: Stardust Dragon has Stardust Xiaolong, Stardust Flash, Stardust Mirage, Starlight Road, and Shooting Star; Red Dragon Archfiend has Crimson Fire; Black Rose Dragon has Thorn of Malice; and Ancient Fairy Dragon has Ancient Sunshine and Regulus.

Members

Despite "Blackfeather Dragon" being the Dragon associated with the Signer, Crow Hogan, it was not present in the ancient battle with the "Earthbound Immortals". There was a different fifth Dragon present in that battle, whose identity has not been revealed.

Assault Modes

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

Example:

Majestic Forms

The Majestic Dragons are upgraded forms of the Signer Dragons, similar to the /Assault Mode monsters, summoned by Tuning Majestic Dragon with one of the Five Dragons and 1 non-Tuner Monster. They tend to have multiple powerful effects, currently being the strongest of all Synchro Monsters, but are balanced out by returning themselves to the Extra Deck during the End Phase while reviving their previous form from the Graveyard.

So far, only 2 have been revealed: Majestic Star Dragon and Majestic Red Dragon, which were both used in the anime by Yusei Fudo and Jack Atlas, respectively.

Examples: