Swiper is a sneaky fox in a blue mask and gloves, who appears in nearly every episode. He is voiced by Marc Weiner. As his name implies, Swiper steals or attempts to steal key items that help Dora on her adventures. Clever as he is, Swiper never manages to take Dora completely by surprise; an ominous “whisking” sound is always audible just prior to his appearances.
To prevent Swiper from success, Dora must repeat the phrase, “Swiper, no swiping!” three times. Usually she prevails, and Swiper slinks away, snapping his fingers and saying, “Oh, maaannn!”; sometimes, however, Swiper gets to the item before Dora has a chance to repeat the phrase. He then gloats, “You're too late!” (and frequently “You'll never find it now! Ha, ha, ha!!”).
Swiper's motive for theft is obscure; he never seems actually to want the object he takes, since he almost immediately throws it away to hide it from Dora (prompting her to ask the audience to help her find it). It is unclear if he swipes merely for the joy of swiping, or from a desire to annoy and frustrate Dora. Compounding the confusion is the fact that, given the right reason — e.g., that the item in question is a present for Dora's puppy — he'll return items he has taken, no matter how much effort he went through to get them. It is also shown that he rarely knows the full importance of what he's taken; e.g. he had no idea the aforementioned gift was for Dora's puppy. He has some kind of New York accent, and lives in a burrow on top of Blueberry Hill (no relation to the song).
Swiper is very fast and agile, and something of a master of disguise. He seems to have a great deal of technical knowledge, as he's built a variety of vehicles and gadgets (including a remote-controlled robot butterfly) to help him swipe things. Most of the time, however, he simply relies on his natural stalking abilities — sometimes with the aid of a costume — to sneak up on Dora. In the early episodes he often “hid” by curling up into a ball, which neither Dora nor Boots ever recognized as Swiper; he apparently doesn't do this anymore.
He has only been seen once without his mask, when the robot butterfly he built to swipe from Dora and Boots (in the episode “Dora's Got a Puppy”) apparently malfunctioned; after they stopped it, it swiped his mask and gloves and kept them from him for a few humorous seconds.
None of Swiper's relatives have ever been seen, but his grandmother has been mentioned in two episodes: “A Letter For Swiper” and “Swiper the Explorer.”
Over the course of the series, it's shown that there's more to Swiper's character than an urge to swipe things. In one episode it was revealed that Swiper has a soft spot for puppies, and in another that he likes Cowboy cookies. In a few episodes, he expresses feelings of joy with a fox-like cry of, “Yip-yip-yippee!” In the episode “A Letter For Swiper,” Dora filled in for a delivery bird whose glasses were broken; Dora delivered stickers to Swiper (which were sent by his grandmother), and he thanked her for it without trying to swipe anything. In the episode “Swiper the Explorer,” Swiper helps Dora on her quest to help Baby Fox find its mommy, and Swiper carries the baby fox almost all through the episode. Also in this episode, it's revealed that Swiper doesn't speak Spanish, and wishes that he did.
The interaction between Dora and the antagonistic fox also reveals the kindness and grace of Dora's character. In one unusual episode, “Dora's Dance to the Rescue,” Swiper took pity on a Dancing Elf who was caught in a magic bottle, similar to a genie. The elf tricked the sympathetic Swiper into removing the bottle's cork, thereby releasing the elf and his talking cane. Unfortunately, the wily fox was thereby entrapped in his place. Stuck and desperate, Swiper called out to Dora and Boots. The remainder of the episode chronicled an epic adventure involving most of the land's creatures, eventually ending with the release of Swiper after a dance contest. The episode was atypical as it involved many dances and songs, demonstrated a close, unconflicted relationship between Swiper and the other creatures, and had Dora refer to the elf in an uncharacteristically judgmental way (“mean Elf”).
In this and several other episodes, Swiper finds himself captured, trapped or in some sort of trouble. Despite his history of mean-spiritedness toward Dora, she demonstrates that the fox is her friend (which he doesn't find out until “Dora's World Adventure”) and will always unquestioningly help Swiper just as she would her other friends, Benny, Isa, Boots and Tico. If Dora needs his help he'll come to her aid in the same manner.
Swiper is far from being unable to feel guilty for his actions. In “Dora's World Adventure,” Swiper helps Dora return the friendship bracelets he'd swiped all over the world, and was shown to feel guilty once he discovered the magnitude of what he'd done and what he'd stolen. During this time Swiper gets a taste of his own medicine, so to speak, as each country they visit has its own “Swiper,” only of different species, who tries to steal the bracelets ; they are Fifi the skunk in France, Sami the hyena in Tanzania, Fomkah the bear in Russia, and Ying Yang the weasel in China. All of them act and dress nearly identical to Swiper and are stopped in the same way he is ; by saying their name, followed by “no swiping” three times. Then they run off, saying Swiper's catch phrase, “Ohh, maann,” in the local language ; this was also their only line. Their entrances are also preluded by a sound, only with local music; e.g. Ying Yang has a chau gong playing. Strangely, they were the only ones Dora didn't give a friendship bracelet to, even though she gave Swiper one.