|"This is the story of Lightning, the swiftest of the dog warriors. The Sky-Dogs watched over him, and protected him... But the Earth-Dog was jealous of Lightning. She thought Lightning had lived too long, and that it was time for him to die so that she could take his life force. But Lightning's speed was so great that he could outrun the Earth-Dog's terrible Growls- he could outrun death itself!"|
|— Mother-Dog to her pups about Lightning in The Empty City Prologue|
| Spirit Dog|
| Species |
|Names|| Warrior-Dog: Lightning
| Status|| Immortal|
|Living||The Empty City, A Hidden Enemy|
In the Original Series
- Lucky's Mother tells her pups the story of Lightning. Yowl boasts and says he bet he could run just as fast as Lightning, while Squeak shushes him.
- During one story time, Mother-Dog tells her pups the story of the The Storm of Dogs. She explains that Lightning was the swiftest of the dog warriors, and the Sky-Dogs watched over and protected him, but that the Earth-Dog was jealous of Lightning, and believed that it was time for him to die. However, Lightning was so fast that he could outrun the Earth-Dog's Growls and even death itself. Yowl murmurs that he wants to be like Lightning, and bets he could run that fast, although Squeak silences him to hear the rest of the story.
- Mother-Dog continues that there came the first great battle, the Storm of Dogs, and Earth-Dog thought that Lightning's life force would be freed and she would take his body rightfully. However, Lightning was cunning and was sure that his speed could help him escape death again, so Earth-Dog laid him a trap. Lightning tried to escape the Storm of Dogs with his speed, and ran so fast between the fighting dogs that not one could see him to attack him. He was almost free when Earth-Dog sent a Big Growl to open the ground in front of him. When Yap heard this part of the story, despite being very familiar with the tale, he heald his breath, imagining that this time Lightning would be eaten up by the earth.
- Mother-Dog goes on that Lightning saw the ground open up to swallow him, but couldn't stop because he was running too fast. Lightning feared the Earth-Dog finally had him, but the Sky-Dogs adored Lightning, and as he started to plummet to his death, they sent a great wind that spinned so fast and strong that it caught Lightning as he fell and lifted him up into the sky, where he remains with the Sky-Dogs to this day.
- At the end of the story, Yowl asks if Lightning will always be there, and Mother-Dog answers that when they see fire flashing in the sky when the Sky-Dogs howl, it is Lightning running down to the earth to tease the Earth-Dog, who will never be able to catch him.
- After Lucky runs from the Fierce Dog, he finds himself lying on the brink of a vast black hole in the earth, and wonders if the Earth-Dog is waiting for him there, the way she had once waited for Lightning.
- Later, when Lucky is with the Leashed Pack and there is a storm outside, he notes that there is a war in the sky, where the Sky Dogs are fighting to the death, and Lightning teases the Earth-Dog by tearing through the sky and leaving fire in his wake. When Bella recounts to Lucky the tale of Omega Wind and the Forest-Dog, she tells him that the Forest-Dog loved Wind the way how the Sky-Dogs had loved Lightning.
- After the dogs find the river store, there is a storm again, and Lucky explains to Sunshine that the storm is actually the Sky-Dogs sending Lightning to tease the Earth-Dog. He explains that the Sun-Dog growls his displeasure and sends the Sky-Dogs and Lightning packing, and then the storm goes away.
- When Mother-Dog tells her pups to stay away from wolves, she reminds them of the story of Nuzzle, who followed the Wild Wolf-Pack, and would have been killed for spying had she not been Lightning's grandpup. Although Lightning had been a Sky-Dog at the time, he still watched over his kin, and when he saw that Nuzzle was in danger, he leaped down to the earth. Lightning set fire to the First Pine and Greatfang, who would have killed Nuzzle. Mother-Dog tells her pups that had that not happened, Nuzzle would not have become Wildfire, and reminds her pups that they cannot rely on Lightning to come and save them, and must learn from Nuzzle's mistakes.
- When there is a storm outside, Yap and his littermates are scared, although their Mother-Dog reassures them that there is nothing to be scared of. She tells her pups that although it sounds frightening, it is only the Sky-Dogs and Lightning play-fighting, and is only a game to them. Yap thinks that it doesn't sound like a game, and frets that they might hurt each other. However, Mother-Dog comforts him that they won't hurt each other and are only having fun. She explains that the Sky-Dogs were littermates and Lightning is their friend, and friends and littermates always stick together. Yowl whimpers that they seem angry, and Snip is doubtful that they are only playing, but Mother-Dog confirms that she is sure of what she is saying. She tells her pups to fall asleep, as the Sky-Dogs will do the same soon. Yap wishes he could ask his Mother more about the Sky-Dogs, but he falls asleep.
- When Yap wakes up, the storm isn't as furious, but his Mother-Dog's face is worried. He guesses that the Sky-Dogs aren't just play-fighting, and Mother-Dog agrees that this storm is different, as the howls of the Sky-Dogs sound deeper. She says that they could be playing, but might be angry. Yap asks who or what they might be angry with, but Mother-Dog is unsure, and adds that a dog might have done something to upset them, and they want to remind the dogs of how powerful they are. Yap wonders what a dog could have done to upset the Sky-Dogs so much, and asks if Lightning, a friend to the dogs, would ever turn on them. Mother-Dog replies that Lightning and the Sky-Dogs are there to protect them, and that the Spirit Dogs, with their sharp instincts, may be howling to warn them of danger.
- Yap is worried at this, but his Mother-Dog tells her pup that whatever is happening, the Sky-Dogs would protect them. When thunder rumbles again, Yap whimpers. He had always admired Lightning, who was brave, loyal, and counted the Sky-Dogs as his Pack, but is now unsure, wondering if Lightning is angry or scared himself. Mother-Dog repeats that she is sure the Sky-Dogs are only play-fighting. When Yap notes that the Sky-Dogs are loud when they play, Mother-Dog tells him that he couldn't expect the mighty Sky-Dogs to play quietly.
- As Yap falls asleep, he remembers his Mother-Dog's fear that the Sky-Dogs might have been howling in warning, and wonders what might have been bad enough to alarm even the mighty Sky-Dogs.
- Later, after Lucky and Mickey rescue the Fierce Dog pups, when they ask him questions about the Forest-Dog, Lucky remembers how as a pup, he, too, had also asked his Mother-Dog many questions about the Spirit Dogs, and his mother would always tell him all about the Sky-Dogs and Lightning.
- When Yap is slightly disappointed that his adult name will be Lucky, Mother-Dog tells him that it is a good name, and she mentions that Lightning was lucky when he was saved by the Sky-Dogs.
- Although Spirit-Dogs have no definite breed, Gillian has described him to be alike an old hunting style Greyhound/Deerhound.
= Gender Unknown