Legend of the Boneknapper Dragon
Thor appears in Gobber's flashback in Legend of the BoneKnapper Dragon, when Gobber is stuck at the BoneKnapper's feet, after Gobber yelled, "HELP!". Thor appears and throws a mighty thunderbolt to the Earth, summoning the Hammerhead Yak & The Hammerhead Whale to help Gobber against the BoneKnapper.
DreamWorks Dragons: Riders of Berk
In episode 13- "When Lightning Strikes", a lightning storm ravages around Berk. Gobber states that Thor must be angry, and the only other time he can remember a lightning storm in Berk is during the time of Jorgern Barnstat. Stoick explains to Hiccup that he was a drifter and a thief who stole from the elderly. When he was fixing the mast of his ship to make his escape from Berk, Thor punished him by striking a thunderbolt right through his helmet. The lightning ended up setting the entire fleet of Berk in fire. And so, the villagers shipped Barnstat off the island and no one has heard a word about him since.
The lightning continues hitting the village, especially the metal perches. A lightning strikes near Toothless and he runs off, spooked. Later, Toothless is seen leaping between the metal perches, barely managing to avoid being struck by lightning. Later in the episode, it is revealed that metal was the cause of the lightning.
"Beard of Thor, What is that?!"- Gobber when he sees the Red Death, How to Train Your Dragon film
"Wait for it..." -Thor, Legend of the BoneKnapper Dragon.