Pakkun

is a petite pug, and the smallest of Kakashi Hatake's Ninken. Despite this, he is summoned the most often, and was the only one of the dogs to be shown speaking in Part I. According to the anime, Pakkun was able to say Kakashi's name at four months of age.

Personality
Despite his cute appearance, his voice is deep and gruff. When Pakkun, Naruto, and Sakura were sent to help Sasuke, he revealed that he is not a battle-type ninja dog, which Sakura claimed to know by looking at his small appearance. In the anime, he revealed that he used Floral Green shampoo (Minty Rain Forest Mist Shampoo with extra body in the English dub), which is also used by Sakura (Sakura was comically traumatized at the thought of using the same shampoo as a dog). In Japanese, Pakkun uses the form of "I" that is used by elderly men (washi).

Land of Waves arc
Kakashi called on Pakkun and the nin-dog pack to track and capture the missing-nin Zabuza Momochi. They managed to grab onto Zabuza by biting him, thus pinning him in place. This allowed Kakashi to use Lightning Blade without fear of a counterattack.

Konoha Invasion arc
During the invasion of Konoha, Kakashi summoned Pakkun again to help Naruto, Sakura, and Shikamaru find Sasuke.

Sasuke Retrieval arc
When Sasuke later defected from Konoha, Kakashi's nin-dog pack was summoned again to track him and Naruto down. Although it was a joint effort, Pakkun was the one who led Kakashi to them. He was summoned a handful of other times in the anime's filler arcs to help Kakashi with his current mission at the time.

Rescue Gaara arc
Several years later, Pakkun and the nin-dog pack were called upon to track down the Akatsuki member, Sasori, using a small piece of his clothing. Pakkun met up with Team Guy and helped them to meet up with Kakashi.

Arrival of the Three-Tails arc
In the anime's Three-Tailed Beast arc, Pakkun was used by Kakashi to communicate with Tsunade, receiving orders and sending her things for study.

Hunt for Uchiha arc
Some weeks later, Kakashi summoned the pack to help track down Itachi Uchiha. Pakkun was the only one to be partnered with Kakashi.

Abilities
Despite his small size, Pakkun has shown to be a very useful summon. He has been repeatedly shown to have an incredibly sharp sense of smell, even by canine standards. He can regularly determine what type of scent he is picking up, how far away it is, and how dangerous the person is. Also, he has been shown to have tremendous speed from how effectively he can keep up with full-grown human ninjas, even challenging others to keep up with him.

Trivia

 * During the invasion of Konoha, Shikamaru refused to help in finding Sasuke. Pakkun told him that, if he completed this mission, he would let him touch the pads on his feet, which he claimed were really soft and supple. This is a reference to modern Japanese culture, in which a dog's paw is considered its cutest aspect; the idea of an animal's paw being "cute", however, applies mainly to puppies and kittens, because at birth their pads are pink, and, as dogs grow older, they turn into a dirty black.
 * In 2005, a Pakkun-shaped controller case was given away as the bonus to those who preordered Naruto: Gekitou Ninja Taisen 4 in Japan.