Mildew

Mildew is a cantankerous, and ugly old viking, the secondary antagonist in the DreamWorks Dragons Series Season 1 and an anti-hero in Season 2. He lived in a small house on the outskirts of Berk, sharing it with a sheep named Fungus. Unlike most of the vikings on Berk, Mildew has a deep, unrelenting hatred for the dragons, and was determined to get rid of them but he is never successful. He is now an Outcast helping Alvin the Treacherous train dragons.

Riders of Berk
He was the most prolific of the Vikings to complain about the Dragons, pushing Stoick to cage them or drive them away.

He taunted Hiccup over the fact that his making peace with the dragons had cost Gobber his position as blacksmith.

According to Mulch, after a storm known as "Blizzard of Orlaf," it took some Vikings a week to dig an unlucky Mildew out of the ice (and the rest of their lives to wonder why they bothered.

Mildew then framed the dragons for destroying things around Berk, successfully causing them to be banished. He makes it look as though the dragons have stolen shoes, wrecked the great hall, and finally destroyed the armory. He used fake dragon props to accomplish his goals. Only Hiccup manages to see these devices. Unfortunately, Mildew then disposes of the evidence by throwing it out to sea. When the dragons are banished Mildew is the only one who celebrates.

Hiccup tries to find the evidence Mildew had disposed of in the last episode, but to no avail. Mildew has the nerve to keep heaping the blame for the lack of weapons on Hiccup and the dragons even after the dragons left, when he learns the Outcasts are offshore of Berk. When Alvin the Treacherous arrives and searches for the "Dragon Conqueror" (Hiccup), Mildew tries to tell him but is knocked out by Astrid. At the end of the episode, he was furious to see the dragons once more- the village having accepted them back after the dragons helped them drive off Alvin's men, but was warned by Stoick, along with Hiccup saying that he may not have the evidence that proved he framed the dragons, but will not forget it, leaving a frustrated and disappointed Mildew.

Mildew was seen buying mysterious items from Trader Johann, in exchange for cabbages. The next day, all of the dragons become ill for an unknown reason. Although everyone throws out what they bought from Johann, the dragons are still sick. Fishlegs tells them that the cause is the blue oleander flower, which is poisonous to reptiles which means poisonous to dragons. Tuffnut says that he saw Mildew plant them at night. When Stoick, Hiccup and Astrid interrogate Mildew, he pretends to not know of the flower's "special properties." Hiccup, Stoick, and Gobber board a ship to find the Scauldron, a dragon that feeds off the oleander, and whose venom can be used as an antidote. Mildew is dragged onto the ship, much to his displeasure, because it was his fault the dragons were sick. When the Scauldron is found, Mildew is threatened by Stoick to wind up with the bucket that's supposed to be used to get the venom or Stoick will throw him overboard. However, before the venom can be drained, the sea dragon escapes, but not before biting Mildew's butt, trying to get the flower that was stuck to his pants. Gobber takes Mildew back to his workshop, and uses a large needle-like object to pull the poison out of the old man, much to his discomfort.

Lightning from thunderstorms strike the metal perches recently set up for the dragons, and seemingly follow Toothless. Mildew accuses Toothless of causing lightning strikes due to his status as 'the unholy offspring of lightning and death' (according to the Book of Dragons), and rallies up the citizens to banish the Night Fury. When Hiccup proves to everyone that the lightning is really attracted to metal, Stoick suggests taking the iron statue of Thor, built to appease the thunder god (but failed), and placing it high up in the mountain, where the gang puts it directly outside Mildew's house. When the next storm comes, the lightning goes through the statue and into Mildew's house, shocking him repeatedly.

It is revealed he set a trap for Hiccup and Toothless by forging a map to an island with Night Furies. It is also revealed he has joined the Outcasts. His method of trickery was personal and devious. He used Hiccup's love for Toothless as bait, and then lured them both into a trap. Not only this but he ensured that none of the other kids would come. His actions alone led to Hiccup and Toothless being captured by Alvin and his men. Upon seeing Hiccup captured, he openly mocks him for falling into a trap set by a silly old man.[9] It is unknown how long Mildew has been in league with Alvin, but it might help explain how convenient Alvin's arrival to the island was before.

Mildew begins to regret what he has done after Alvin locks him up and takes away Fungus to be cooked as his final meal. He then helps Hiccup escape, and both Hiccup and Mildew work together and befriends a Deadly Nadder with Hiccup's help. "Unfortunately", Mildew is dropped from the Nadder that Gobber is riding, and falls back onto Outcast Island as the gang is making their escape. Later, it is revealed that he and Fungus were all putting on an act, so that he could learn all the dragon training secrets from Hiccup. Mildew truly is a traitor to Berk. He then begins to tell Alvin the information he learned from Hiccup. With that information, Alvin was able to train a Whispering Death.

Defenders of Berk
Mildew came up with the idea to plant a cluster of Whispering Death eggs in a underground network of tunnels so that they would hatch and destroy Berk. He and Savage oversaw this plan being put into action while Alvin and his wild dragons distracted the dragon riders, but what he was unaware of was that one of the eggs was a Screaming Death egg.

Mildew, Alvin and Savage infiltrated Berk to investigate what happened with their previous plan, which, unknown to them, resulted in the creation of the Screaming Death. Mildew managed to save himself from Alvin's wrath by suggesting they use the tunnels to infiltrate the Dragon Academy to kill, spy and kidnap and, later on, helped the other two to kidnap Meatlug, who had been neglected by Fishlegs at the time. When tried to make their escape, he was knocked unconscious by Butt and Head, who had been trained by Ruffnut and Tuffnut, and only came around to see that they were all drifting on wreckage. Alvin immediately knocked him unconscious when he tried to make them look on bright side.

Mildew then oversaw the training of the Skrill when Alvin formed an alliance with the Berserkers.

He was then seen feeding a Whispering Death as he showed Hiccup where the eggs came from that were planted under berk and asking if there was a giant red egg Screaming Death egg and was later seen fighting Dagur and his Berserkers.

Personality
Mildew is a consummate complainer; Gobber even said of his arrival "Here comes Mildew with the complaint of the day." It is implied that Mildew's house was built so far away from the village because of his abrasive personality. In fact he is the most unpleasant person on the island of Berk. He is even worse than Snotlout. In fact he has few if any redeeming qualities.

Due to his staff decorated with dragon teeth, and the fact that he had a pair of Zippleback feet, a Monstrous Nightmare claw, and a Gronckle head in his house, it can be inferred that in his glory days he was an excellent dragon-slayer, this would explain why he is so rude and arrogant.

Mildew also seems to dislike Hiccup, probably due to Hiccup's befriending of the dragons, and seems to relish the idea of Hiccup being gone, as evidenced by his attempt to turn Hiccup over to the Outcasts in Alvin and the Outcasts. It is also evidenced when he turns the entire village against Toothless in "When Lightning Strikes". This dislike reaches a peak when Mildew actually betrays the entire island of Berk by sending Hiccup into a trap set by Alvin. And he had the gall put the blame for his behavior on Hiccup for befriending dragons.

Mildew hates dragons more than anyone else on the island, and he talked about holding a party to celebrate the banishment of the dragons from Berk. And he was the only one who was not happy about the dragons returning. In fact Hiccup's words "There are those who will never accept the dragons, and will do anything to drive them away." proved to be all to prophetic in many situations.

Mildew is also frightened of certain dragons, in Dragon Flower, He was scared of the Scauldron that Hiccup and the other vikings were trying to get some venom from, which later bit Mildew on the backside. Also, a Whispering Death snarls at Mildew, which involved Mildew running away on a Deadly Nadder.

He also seems to not particularly care about the feelings of other people, as he was openly gloating about the banishment of the dragons while everyone else was miserable.

He has also proven that he will go to any lengths to get rid of the dragons, even treachery.

His alliance with the Outcasts seems to have wrung the complaining out of him, mainly because Alvin might kill him for complaining.

Role in the series
Mildew still lives with Alvin, though he doesn't appreciate him being reformed, and wants to be back into the business of being evil. He even had a friend in the form of Grimoors the Nasty Mouthed, both sharing the same hate of dragons, but was disgusted that he hypocritically used one to get the job done, even if he believed he was planning to kill it afterward.