Hookfire

"As awesome as Hookfire, Fangmaster and Hook Blazefang are... and I named them all already, I can't look at them and not think of Hookfang."

- Snotlout naming the three dragons

Hookfire is a Monstrous Nightmares that Snotlout named when the other Dragon Riders tried to find a replacement for Hookfang.

Replacements for Hookfang
In "Total Nightmare", Hiccup thought that Snotlout needed a replacement dragon when Hookfang "ran away". When Hiccup brought in Hookfire, Snotlout named them after Hookfang and rejected him.

Physical Appearance
Hookfire is light green mixed with yellow.

Trivia

 * Hookfire's coloring resembles that of Firescrapes and Whip-Slash.