Lurke

"You haven't seen the last of me!"

- Lurke to the Rescue Riders before flying off in "Boo to You".

Lurke, or the Phantom Fang, is the main antagonist of the first season of the DreamWorks Jr. TV series, Dragons: Rescue Riders, which is non-canon to the rest of the How to Train Your Dragon franchise. He is the leader of a trio of Slinkwings who enjoy causing trouble just for the sake of it.

Background
Not much is known of Lurke's past, but it is revealed that he has been terrorizing the village of Huttsgalor and inspired the legend of the Phantom Fang. It also turns out that he, Snoop, and Viza, have been trying to raid Grumblegard's home for years.

Dragons: Rescue Riders
In "Boo to You", a woman named Marena tells the story of a terrible ghost named the Phantom Fang and assures the Rescue Riders that he is real. Eventually, they face the Phantom Fang who turns out to be a Slinkwing named Lurke, who combats the Rescue Riders and flees, but not before telling them that he will be returning soon.