Dagon

Diagon is believed to have visited Earth many years ago and gave humans advanced technology. He is believed to have sworn to come back to Earth and bring the "Golden Age". He said he will bring alien tech so Earth have no war, no disease, just peace. Vilgax was mistaken for and later pretended to be Diagon in The Flame Keepers' Circle.

Diagon is in fact an extra-dimensional monster who tried to invade this dimension with help from many Lucubra during Earth's Medieval era. He was banished back to his dimension when Sir George defeated him by cutting out his heart with Ascalon, a powerful weapon given to him by Azmuth centuries ago.

Appearance
Diagon is shown to look similar to Vilgax's true form; a giant squid as Ben finds Vilgax in the secret room inside head-quarters of the Flame Keeper's Circle to whom the members of the cult worship as the knowledge bringer. But later in A Knight to Remember, Diagon took control of Gwen and uses her to communicate with Ben that Vilgax will attempt to steal the source of his strength, his heart. After that, Driscoll tells Ben that when the First Knight fought Diagon, he reveals that Diagon's true form is somewhat like a Dragon. Diagon scares Gwen as seen in A Knight to Remember, and scared Ben, Gwen and Kevin into demanding Azmuth to get them away in Solitary Alignment. Azmuth and Sir George do not seem to be scared of Diagon. They have probably gotten used to the sight of it.

History
Diagon's voice appeared in The Enemy of My Frenemy, being called by the name Old One, a being who can bring dead persons back to live.

Charmcaster gave him six hundred thousand souls (from every living thing in Ledgerdomain except herself) and in return, asked to bring her father back. Spellbinder disapproves her attitude saying that his daughter became worse than Adwaita. Spellbinder says that he can't stay in Ledgerdomain knowing that his life was bought by the cost of so many others and decides to leave again. Charmcaster says no, but Spellbinder returns to the dead and the Diagon makes all souls return to their bodies, saying that "such is the way of magic".

Powers and Abilities
Diagon has the power of mind control like the Lucubra, but more powerful. His heart is said to have power enough to rule the whole universe.

Diagon is also shown to have powerful fire breath.

Appearances

 * A Knight to Remember (flashback)
 * Solitary Alignment (shadow)
 * The Enemy of My Frenemy (voice)
 * The Ultimate Enemy: Part 1
 * The Ultimate Enemy: Part 2

Trivia

 * Diagon is named after the mythological Dagon, a supernatural being who has taken many identities such as the Semitic grain and fish god and a major member of the Philistine Pantheon.
 * Diagon himself appears to be based on the Dagon from H.P. Lovecraft's short stories which subsequently lead to the popular image of Dagon.
 * When Diagon was first mentioned, it was said that he looked like a giant squid like Vilgax, but then to relate back to George's character was said that he was a dragon.
 * In A Knight to Remember when Vilgax obtained Diagon's heart, Diagon made Vilgax go to his dimension.
 * Diagon shares some similarites with Cthulhu: both are aliens, both have mind controling powers and both look like a octopus.
 * Diagon having no heart is similar to Davy Jones (Pirates of the Caribbean) having no heart either.
 * Also of note Davy Jones, particularily his head, also slightly resembles a squid.
 * Diagon's dragon form is similar to that of Malchior of Teen Titans animated series.
 * Diagon has been confirmed in the credits of The Enemy of My Frenemy as "the Old One".