Marvel's King in Black storyline is underway with an epic struggle between Knull, the god of the Venom symbiote, his army of symbiote dragons, and the haggard group of remaining heroes left on Earth. Knull wants to drench the universe in darkness, and the only thing standing between him and his goal are Earth's superheroes and their allies. But as the body count for King in Black has grown, things are looking more and more uncertain for some of Marvel's most beloved characters.
One facet of Knull's invasion has been his use of symbiote dragons. The dragons have been one of the most challenging aspects about The King in Black because they pose an immense challenge to heroes who cannot fly. Moreover, once the dragons are killed, their symbiote can infect nearby humans, turning them into members of Knull's hive and deepening what is already an immense crisis on Earth.
Still, it is possible to bring down Knull's dragons, and King in Black is not the first time they have surfaced in Marvel history. These dragons were created from the Grendel symbiote, originating from just one symbiote dragon named Grendel, who ravaged the universe with Knull many centuries ago. When Grendel appeared in sixth century Scandinavia, Thor killed him with lightning, forming the basis of the epic poem, Beowulf, as covered in Donny Cates's Venom series. Centuries afterwards, the frozen body of this Grendel was found by S.H.I.E.L.D., who used its symbiote to try to create super soldiers during the Vietnam War (Web of Venom: Ve'Nam #1 by Donny Cates, Juanan Ramirez, Felipe Sobreiro, and VC's Clayton Cowles). Because Grendel has the ability to create others from his original body, he has supplied Knull with his own dragon army. As of right now, it is impossible to quantify just how many there are, but they have wrought havoc on all corners of the Marvel Universe.
So far, the symbiote dragons have provided a number of shocking moments in King in Black. One killed the leader of the United Kingdom's brand new superhero team, Britannia, in the very first issue of The Union, but not before she landed the first killing blow (written by Paul Grist, pencils by Andrea Di Vito with Paul Grist, inks by Drew Geraci, Le Beau Underwood, with Paul Grist, colors by Nolan Woodard, and letters by VC's Travis Lanham). Another one, in a gory turn of Thunderbolts #1, ate a member of Wilson Fisk's villain task force, Snakehead (written by Matthew Rosenberg, art by Juan Ferreyra, and letters by VC's Joe Sabino).
With regards to what does work against the symbiote dragons, past success has been found with heroes who can manipulate light, or sources of it, like Thor, Star (Ripley Ryan) from The Thunderbolts, the X-Men's Wiz-Kid (Takeshi Matsuya), and Star-Lord (Peter Quill). Still, Britannia from The Union managed to kill one by cutting off its head with her sword, but it is unclear if her sword has any special properties that made it so effective against the symbiote. With the storyline's events now headed in the direction of Marvel's own Godzilla, American Kaiju, in King in Black: Planet of the Symbiotes, other potential weaknesses of the Grendel dragons remain to be seen.
The symbiote dragons are a unique part of The King in Black, and what makes them such compelling enemies against the heroes is that they put a spin on a classic sense of evil. As what can be seen with Beowulf, and Britannia's invocation of the dragon-slaying St. George, the Grendel dragons fit an old villain archetype that heroes of yore had to overcome through physical combat. The main difference, however, is that these dragons are much more difficult to defeat, and in Britannia's case, care not for playing a part in classic tales of heroism. With older tales of good triumphing evil completely thrown out of the window by the dragons' fearsomeness, King in Black has shaped up to be a storyline full of twists and turns that has kept both hero and reader guessing what comes next.