Species: NightFury

"The un-holy offspring of lightning and death itself, do not engage this dragon, Your only chance of survival: hide and pray this beast does not find you." - From the "Book of Dragons"

Toothless is a Night Fury dragon. He was shot down by Hiccup, who used a powerful net launcher. Toothless and lost part of his tail through this, making him unable to fly on his own. Hiccup eventually trained himself to ride Toothless and helped him fly again.

When Hiccup was in danger, Toothless risked his own life to run and save the human. He succeeded, but was captured by Stoick and forced to lead the Vikings to the Dragon Nest. Toothless evenutally helped Hiccup kill the dragon "queen", saving Hiccup's life and helping dragons and Vikings unite.