Harold Humdinger was the main villain in the Paw Patrol one hour special (though released to theaters as a film overseas), Mighty Pups, and one of the primary antagonists in its sequel series Mighty Pups, Super Paws. His ultimate goal in the film was gaining more power and ruling over Adventure Bay, his goals in Super Paws varied from cutting Adventure Bay in half and have the town drift out to sea so that he can rule it as mayor, to freezing everyone in town so that he can take over.
Harold Humdinger is the nephew of Mayor Humdinger, ruler of Foggy Bottom. He is shown to be a child prodigy with genius level intellect, thus making him somewhat arrogant. When a meteor crashed on the beach in Adventure Bay after it collided with Mayor Humdinger's intended rocket to the moon, Harold and the Paw Patrol, who were on hand to investigate after clearing the streets, get bombarded by a blast of energy. As a result, all those involved get super powers. Though jealous at first thinking that he didn't get any powers, he changes his mood when he learns he has the power to create any gadget/machine he wants.
After exposure to the meteor (now recently dubbed the Mighty Meteor), Harold gained the ability to create any machine or gadget he wanted with his energized hands, somewhat like Forge from the X-Men, with the only exceptions being his decision on how to use his powers and he creates his machines with his hands instead of just coming up with them and taking the time to build them like normal. It is also revealed, in a Mighty Pups short called Pups vs A Super Meow Meow, that he can easily regain his super suit by just powering up. However, he decided to use these powers for evil purposes. First, he attempted to steal the Mighty Meteor from Adventure Bay Town Hall with his uncle, so that way Mayor Humdinger could get super powers too and be the first super powered mayor. However, though they nearly escaped in a super vehicle that Harold created the previous night before the heist, they were defeated by The Mighty Pups. Mayor Humdinger managed to avoid capture, but Harold didn't, at first. Harold escaped from his captors and broke into the Lookout, created a super suit, captured Ryder, locked him up, and successfully stole the Mighty Meteor once again, while also taking his uncle from Foggy Bottom and showing him his accomplishment. After revealing his traitorous ways by going back on his word to give his uncle super powers and revealing his intent of ruling Adventure Bay, Mayor Humdinger reminded him that he captured Ryder, and the pups would stop at nothing to free him. This resulted in Harold creating a giant robot (which looked somewhat and functions like one of the Sentinels from the X-Men comics), powered by the meteor, to defeat and capture the Mighty Pups.
Defeat and eventual returns
Ultimately, Harold was defeated by the clever pups, after crashing back down to Earth with the Lookout after he accidentally sent it into space with his robot. After his defeat, he and the pups realized that their powers were gone, due to the robot draining the remaining energy out of the Mighty Meteor. Harold and Mayor Humdinger were sentenced to clean up the mess they caused. Afterwards, Mayor Humdinger went back to his old mischievous ways and began working with the Kitten Catastrophe Crew again. As for Harold, he went back to Foggy Bottom after losing his powers. As for the Mighty Meteor, it went into the Lookout basement after being drained, to avoid any more robberies. However, after the pups left the space rock in the basement, it began to glow again, indicating that it recharged itself.
The Mighty Pups and Harold returned to their super powered selves in the debut episode of the Paw Patrol sub-series and sequel series to Mighty Pups the Movie, Mighty Pups, Super Paws, which debuted on Nickelodeon on June 28, 2019. While the pups could access their powers from the Mighty Meteor anytime they chose, Harold had his powers temporarily. After his plan to cut Adventure Bay in half and off from the mainland with a high-powered laser failed, his super powered hench-kitties, The Kitten Catastrophe Crew, who gained their powers along with Harold from a fragment of the Mighty Meteor when it crashed, intentionally knocked the fragment into the ocean, after they lost their powers when Harold dropped the fragment, and made it seem that his villain days were over. However, he regained his powers and began a new plan to freeze Adventure Bay solid so that he could take over, much like what Mister Freeze, Killer Frost, Captain Cold, and Icicle would do to any city in the DC universe. However, when he was defeated and managed to escape, he dropped his meteor fragment into the waters of the bay, losing his powers and sending it back to the bottom of the sea, while Harold himself ended up landing in the arctic in his rocket chair.
After finding his way back to Foggy Bottom from the Arctic, Harold Humdinger found a fragment of the Mighty Meteor and regained his powers, he then set about recreating his Sentinel-like robot in order to steal the buildings of Adventure Bay by using a teleporter ray incorporated into his robot's right arm in order to create his own town, Haroldville. However, he was defeated by the Mighty Pups and their new charged up powers from their battle against The Copycat.
Some time after his fourth defeat, Harold regained his powers and created a cloning machine. He planned to use his machine to clone himself and rule a town populated by copies of himself, but his uncle stumbled upon it and entered as one, and came out with multiple copies of himself. However, the clones showed that they were loyal to no one, even the original Mayor Humdinger, even though they agreed to get some tuna for the Kitten Catastrophe Crew, and they proceeded to steal Katie's Pet Salon. However, thanks to the Mighty Pups, the horde of Humdinger clones was stopped, Katie, her cat Calie, and the pet salon were saved and Harold lost his powers once more. Harold then tried to turn the Adventure Bay Lighthouse into a rocket ship, only to be thwarted and lose his powers again due to the Mighty Pups' interference.
His ultimate plan came around when he teamed up with Ladybird and Copycat in order to steal the Mighty Meteor and both render the pups powerless and allow him and his fellow villains gain more power. By using special power badges created by Harold, the three villains were able to regain their powers and keep them, without having to worry about losing a fragment of the Mighty Meteor. However, due to the greed and visions of power of all three of the villains, the Mighty Pups managed to regain their powers, stop the villains, and both Harold and Ladybird lost their power badges while Copycat made his escape.
Afterwards, he tried taking over Adventure Bay by using a Super Sonic Sound System attached to his super vehicle to force people in Adventure Bay to start dancing so that no one could stop him from taking over the town once he lead all those under his power to Foggy Bottom ala The Pied Piper, but he was halted by Ryder, Chase, and Rocky of the Mighty Pups. His next plan began when Copycat used his own powers to return Harold's powers to him so that he could create something for the Adventure Bay Makers Meet, and what Harold created was a platoon of five miniature robots, which went on a rampage all over both the contest and Adventure Bay. But once more, Harold and Copycat, who were working together when Copycat returned Harold's powers, were stopped by Rubble and Marshall of the Mighty Pups. Soon, Harold manages to fish a meteor fragment our of the water, but when he pulls it out of the water, it flies straight into his uncle's lair and lands inside of his uncle's robotic cat, Meow-meow. Soon, Harold realizes that the robot gained the same powers as the Mighty Pups (essentially making it a robotic version of Copycat) and the robotic cat returns Harold's powers to him. Soon, with Mayor Humdinger providing a distraction with a fake meteor to keep the Mighty Pups busy, all the villains head to the Lookout in order to steal the Mighty Meteor. However, Skye and Zuma charged up and defeated Harold and Meow-meow, and sent the meteor fragment flying out of the robot cat, and also forcing Mayor Humdinger and the Catastrophe Crew to retreat. Then, on a night when the rare and magical Merpup moon rises into the starry sky, while Captain Turbot and Wally watch the Mighty Meteor while the Mighty Pups upgrade the security at the Mighty Tower to protect it, Harold snuck in from under the ocean waves and stole it, only to drop the crate containing it and stumbling upon it after it landed in the legendary underwater city of Puplantis, the home of the Merpups. Once he regained his powers, Harold created a throne, crown, and staff for himself and proclaimed himself King of Puplantis. However, the Mighty Meteor landed inside the clam that created the magical pearls that give life, magic, and power to Puplantis, causing the clam and the pearls it created to grow huge. Ultimately, the Mighty Pups dethroned Harold and saved both him from being crushed by the pearls and the city of Puplantis from crumbling apart due to said pearls.
- According to his uncle, the Kitten Catastrophe Crew are his cousins.
- Harold's plan to cut Adventure Bay off from the mainland with a high-powered laser and rule it as an island is sort of similar to Lex Luthor's plan to use a missile to break California off from the rest of the USA and sink it into the Pacific Ocean in order to sell land that he purchased in the 1978 Superman feature film. The only difference was the method of separation and the fact that Lex intended to see all the people of California drown after the missile hit.
- Harold's plan to steal buildings to create his own town seems like a smaller scale version of Brainiac's usual role of capturing entire planets by means of digitization.
- Harold's plan to lead all the citizens of Adventure Bay to Foggy Bottom is similar to a plan that either the Pied Piper or The Music Meister would pull off in the DC Universe.
- Harold's plan to rule over Puplantis as king is similar to what Ocean Master or Black Manta would do in the DC Universe.