Smidvarg is a male Alpha Night Terror who lives on Dragon's Edge. When Hiccup Horrendous Haddock III and his team of dragon riders arrive on the island, they discover the Night Terrors. At first it is believed that they together were all one big dragon, but were then discovered to be a bunch of little ones. After Hiccup captured Smidvarg and an incident with Changewings occurred, Smidvarg and his flock became allies to the riders, who now act as "sentries" on the Edge.