Tiamat

Tiamat is an enormous and extremely powerful six-headed dragon originally created by the titans to serve as the ruler of all dragons. Each of her six heads represented one of the dragonflights, and was both colored appropriately and possessed the dragonflight's breath weapon. She possessed two pairs of powerful wings, capable of producing gusts of wind strong enough to topple entire armies.

Overview
While creating the six dragonflights the titans quickly realized they required someone to watch over and direct their draconic progeny. The number of dragons was quickly growing to be too much for any one titan to handle, and thus they required an overseer. A queen from where a second generation of dragons would come.

However, the titans slowly began to realize that as Tiamat produced more and more broods, she became increasingly unstable. When her newly spawned progeny began to ransack the worlds they were supposed to protect, the titans intervened. A raging conflict ensued that encompassed over a dozen planets and moons. The Iron Knights were called in to systematically hunt down and destroy the rogue dragon broods.

Eldre'Kar, a young titan and fresh to the Physical Realms, was the one to lead the charge against Tiamat herself. She had made her home within the titanic watch-fortress of Entharadan, there she spawned countless dragons and sent them out into Wildspace. They roamed and pillaged, conquering worlds and enslaving species. Her lieutenants brought back riches and magical artifacts, all of which adorned the alabaster halls of the fortress.

Eldre'Kar had brought in three legions of Stoneborne, a regiment of Iron Knights, and several loyal dragon broods. Alongside Eldre'Kar fought Salon'Ador and Dren'Therel, each bringing their own retinues to battle. The siege of Entharadan was immense, spanning across the entire solar system.

Unbeknownst to the titans, Tiamat had discovered a way to splice together humanoid and draconic DNA. She had created a legion of over 10,000 dragonkin who were fiercely loyal to her and her broods. She used these dragonkin to construct great star vessels to engage the titan's forces as they entered the solar system. Tiamat's forces inflicted immense casualties on the Stoneborne, and destroyed nearly every Iron Knight present. However, Eldre'Kar prevailed by personally leading the charge through Tiamat's battle-lines. His flagship engaged a flight of Tiamat's most elite of white dragons, killing the majority of them.

After breaking through Tiamat's lines, Eldre'Kar tore a bloody swath through the solar system. In just two short days, he had liberated Entharadan and the surrounding planets. He, alongside Salon'Ador charged Tiamat's birthing chamber and defeated her in combat.

Wanting to discover what went wrong, rather than kill Tiamat they captured her. While the conflict for the solar system raged, Dren'Therel was tasked with constructing an arcane vault that could properly imprison Tiamat. After marching out of the half destroyed watch-fortress, the three titans quickly imprisoned Tiamat in her magical cage. They transported her to Prima'Thaad, another watch-fortress located deep in Sentinel-controlled territory.

Unfortunately, the three titans were recalled to the front-lines to deal with a particularly devastating Black Order invasion, leaving Tiamat in permanent stasis.

Aftermath
Tiamat's legacy was one of violent and bloody conquest. Hundreds of thousands died, many thousands more went missing. Not all of her rogue broods are accounted for, and many dragonkin took their ships and fled to the stars once Tiamat had been captured. Those few dragonkin ships that are still working pillage every world they come across. Many dragonkin settled or crashed onto planets, unable to maintain their vessels without draconic assistance.

In the intervening years, many dragonkin formed into tribes and warbands. Their ability to quickly reproduce and high gestation rates made them an implacable foe. They are located across countless worlds, and are viewed as a plague by indigenous populations.

Every now and then a dragon of Tiamat's brood will stumble across a world and settle. There they gather in secluded places, bundled under piles of gold and artifacts pilfered from nearby civilizations. When a rogue dragon is discovered, typically the planet's native dragonflight will deal with it, though this often proves to be easier said than done as the rogue dragon often has decades if not centuries of combat experience.