Pixl

Pixls are an ally species of Mario and company. Their first, and currently only, appearance is in Super Paper Mario. In this game, the Pixls help Mario, Peach, Bowser and Luigi by giving them special moves, like picking up items or enemies and throwing them, serving as explosives, or even acting as a floating platform for Mario and the others to ride on. The playable Pixls are Tippi, Thoreau, Boomer, Slim, Thudley, Carrie, Fleep, Cudge, Dottie, Barry, Dashell, and Piccolo. Tippi stays on the player's team all the time, except on a few occasions, such as when she is captured by Francis. Later, Tiptron replaces her, and it would always stay active.

Each Pixl is very bright and has its own unique shape. Tippi looks like a   butterfly and Thoreau is a hand (a square with five small circles on its top half). Boomer resembles a bomb with wings. Slim is an upside down triangle (he also strangely resembles a spiral) with wings. Thudley looks like a 100-ton steel block with two circular eyes floating above. Carrie is made up of a bunch of small squares, that, when folded the right way, turns into a cube platform. Her face is the middle square, and she also has wings. Fleep looks like a big rectangle with wings and a tail. Cudge looks like a hammer with wings. Dottie is a ball with many long rectangles spread around her. Barry is a spiky circle with a sad face. Dashell looks like a missile with two eyes. Piccolo is a music note with wings.

Pixl Uprising and Creation
3,000 years before the setting time of Super Paper Mario, a powerful magician among the Ancients created the first twelve Pixls. He accomplished this by transferring a spirit (thought at a time to be those of people, possibly humans or Flip-Flop Folk, who had been given Game Overs, though this theory has apparently been disproven) into a vessel that he created for a specific purpose. Even after his death, his apprentices learned how to make many more Pixls based on the powerful magician's original twelve. They became known as "thinking tools" for the Ancients, who eventually became rather dependent on their Pixl helpers. Through the work of many Pixls, the Ancients prospered as they never had before.

One day, however, a catastrophe occurred. A huge Pixl, calling herself the Pixl Queen, suddenly appeared. At her command, Pixls everywhere (seemingly under mind control) rebelled against their Ancient masters. Most Pixls were well-contained spirits, but she was a demonic spirit (apparently one of a human) contained in a Pixl vessel. She had the power to command all the other Pixls, and the Ancients had become so dependent on the Pixls that they were devastated. They suddenly lost their ability to effectively build and rule their empire. The Pixl Queen enslaved the Ancients.

In the midst of the ruin, the inheritors of the twelve original Pixls appeared, defeated wave after wave of Pixl soldiers, and freed the enslaved Ancients. They used Catch Cards to trap the mind-controlled Pixl soldiers and then healed them. They saw their friends fall in battle one by one, yet preserved anyway. The last survivor managed to make it to the castle of the Pixl Queen.

The Pixl Queen used her powers of illusion to hide and unleashed horrific images upon the surviving freedom fighter. One of the Pixls at his side was immune to this and helped the survivor fight; his Pixl finally defeated the Pixl Queen, tragically ending its game in the process.

The vanquisher of the Pixl Queen was confronted with an awful truth: the Pixl Queen was actually the very first Pixl ever made. The master magician had made her after studying the Dark Prognosticus. The survivor, who was therefore likely to be one of the people who would later found the Tribe of Darkness, decided to disappear with the book so that this type of disaster would not happen again. The Ancients continued to fear the Pixls, however. The Elders of the Ancients decided to limit the power of all Pixls and outlaw their creation. Eventually, the Ancients' influence and power declined till they were no more.

Trivia

 * The name "Pixl" comes from the word "pixel"; a pixel is the smallest possible portion of an image. It is also likely derived from "pixie", an alternate term for "fairy".
 * Each Pixl's name comes from the ability they let Mario use.
 * Tippi gives Mario Tips.
 * Thoreau allows Mario to Throw.
 * Boomer is used as a bomb with a boom.
 * Slim allows Mario to go paper Thin (in other words Slim).
 * Thudley allows Mario to ground pound with a thud
 * Carrie turns into a platform to Carry people over obstacles.
 * Fleep can be used to flip objects from one dimension into another.
 * Cudge allows Mario to use him as a hammer/Cudgel.
 * Dottie has the ability to shrink Mario to the size of a dot.
 * Barry creates a Barrier around Mario & friends.
 * Dashell provides speed boost. (Name comes from Dash and Shell)
 * Piccolo plays music that can cure status alignments. (Piccolo is the name of an instrument.)
 * Mario happens to be aided by exactly twelve Pixls during the events of Super Paper Mario, making it rather likely that Mario's Pixls are indeed the first twelve. However, this would actually be impossible, as Tippi is known to have not always been a Pixl and Cudge, too, subtly suggests that he wasn't always a Pixl (though his statement about feeling like "when he was first became a Pixl" may have related to the propulsion of his spirit into a Pixl vessel rather than a more direct transformation). Even still, though, the two uses of the number twelve make an interesting coincidence to note and may be intentional.
 * When Mimi impersonates Merlee and tries to trick Mario into accepting an offer, she mentions "Breadward, a Pixl made of oats and lard." Yet another unseen (and, in this case, unnamed) Pixl is mentioned by Heronicus; speaking to him after the game is beaten will reveal that he spent much of his life seeking a legendary Pixl which he did indeed once find. However, a rockslide happened just as he had found the legendary Pixl, and he decided to save his partner rather than it.
 * Pixls apparently do not need oxygen–– When the heroes first enter Outer Space, Tippi and the other Pixls are not bothered by their lack of air. Even when they acquire the Space Helmet, the Pixls have no breathing device. It would also appear that Pixls have immensely long (or perhaps even infinite) lifespans, as most of Mario's Pixls existed for at least 1,500 years.
 * While Super Paper Mario was in production, various unofficial websites referred to the Pixls as Fairens (likely basing on their Japanese name of Fairin, which actually can mean "fairy" or "sprite" when translated from Japanese), although it is unknown if this name was ever actually in use by Nintendo. It is also known that, while Super Paper Mario was on the GameCube, Pixls would be activated with the GameCube's X Button rather than the 2 Button of the Wii (although it is unknown how Tippi would be activated), and a mysterious, ladder-shaped Pixl not present in the final game also appeared in a certain beta screenshot.