Dragonicus is one of the legendary Guardian Knights. With his comrades, he can form the mighty Dragonstorm.
The Last Knight
At least two separate Guardian Knights use the Dragonicus design; with none of them named on-screen, it is impossible to know which, if any, is the Dragonicus.
After betraying their supposed creator, Quintessa, Dragonicus and the Guardian Knights fled with her staff to Earth, in truth the dormant form of legendary Transformer Unicron. Sometime in the late 5th century, the human "wizard" Merlin stumbled upon the knights' spaceship, buried beneath the hills of England. He met the Knights and learned of their homeworld of Cybertron, but promised to keep their existence a secret from his peers.
In 484 AD, Merlin returned to the ship and made a heartfelt plea to their leader Stormreign, seeking aid for King Arthur and the Knights of the Round Table in a dire battle against the Saxons. As Stormreign bestowed upon Merlin the very staff they stole from Quintessa, Dragonicus joined the other knights in forming Dragonstorm to fight alongside Arthur's men, winning them the day. In the battle's aftermath, the Knights of the Round Table forged an alliance with the Guardian Knights, beginning a heraldic order which would become known as the Order of the Witwiccans. On at least one occasion, Dragonicus charged into battle alongside Arthur's men. Sir Edmund Burton's collection included an excerpt of the Bayeux Tapestry which appeared to show Dragonicus and the other knights fighting in the Battle of Hastings in 1066 AD. Eventually, the Guardian Knights moved their ship underwater and entered a centuries-long slumber, guarding Merlin's remains and the staff Stormreign had granted to him.
In the modern day, the spaceship was located by Merlin's last descendant, and the knights awoke, Dragonicus among them. After Quintessa successfully reclaimed her staff, intending to use it to transfer energy from Earth/Unicron into the desolate Cybertron, Dragonicus and the Knights joined the Autobot mission to stop her, combining into Dragonstorm from atop the deck of the Autobot ship. As part of Dragonstorm, Dragonicus helped the Knights' Autobot and human allies by taking out enemy fighters and dropping Optimus Prime into the battlefield to vanquish Infernocus. After Quintessa and Megatron were defeated and their plan was foiled, Dragonicus and the Knights merged into Dragonstorm and departed Earth for Cybertron alongside the Autobots.