I'll probably be on this floating island forever, guarding the Master Emerald again. I may not know the whole story behind this, but perhaps it's better that way.
— Knuckles the Echidna, Sonic Adventure
Knuckles the Echidna (ナックルズ・ザ・エキドゥナ, Nakkuruzu za Ekiduna?) is an anthropomorphic echidna from the Sonic the Hedgehog universe. He is the current guardian of the Master Emerald, a powerful ancient relic which is his solemn duty to protect from anyone seeking to abuse it. He is also the sole remaining descendant of the Knuckles Clan and last of the echidnas on Earth. His dominant traits are his superhuman strength, and the two spike-like knuckles on each of his hands, from which his name is derived from, which he can use to dig with and climb walls. He can also trap the wind under his dreadlocks to glide through the air.
A loner by nature, Knuckles is independent, headstrong and serious, yet gullible and short-tempered to a fault. He is entirely devoted to his duty, spending most of his time on Angel Island protecting the Master Emerald, and rarely cares for anything that is of no importance. When his friends and others are in need of his help, however, Knuckles can always be relied on being willing to leave his post and prove himself a faithful and good-hearted hero. He is also one of Sonic the Hedgehog's oldest friends and rivals.
Knuckles is an anthropomorphic echidna with red fur that covers most of his body, peach skin that covers his muzzle, and white fur that covers a small part of his neck, and purple eyes. He also has seven spines and a medium-sized tail along with spiked knuckles.
He wears red and yellow shoes with green cuffs and a grey plate on top. He also wears white gloves with a sock-like cuffs on his hands.
Knuckles was born alone and raised on Angel Island as the last surviving member of the Knuckles Clan, a long-lost race of echidnas devoted to protecting the Master Emerald from being abused. However, Knuckles's own past was a mystery to him; he knew nothing about how he came to be and believed himself to be the last of his kind entirely. The one thing he did know was that he had always been living on his island, protecting the Master Emerald. Knuckles knew from an innate knowledge that his duty was his fate, and he was content with that.
For much of his life, Knuckles stayed close to the Master Emerald's shrine, steadfastly protecting it while having little to no contact with the outside world, becoming friends with all the animals and the nature itself on Angel Island.
Sonic the Hedgehog 3 & Knuckles
Sonic the Hedgehog 3
Knuckles was on his usual patrol of the island's pillar, watching over the Master Emerald and the seven Chaos Emeralds, when a Chaos Emerald started to float and vibrate as tremors began. Then, in an ear-piercing crash and brilliant flash, Knuckles was knocked unconscious. When he came to, Knuckles found the altar partially destroyed and the Chaos Emeralds missing. Shocked, Knuckles investigated the island and discovered the Death Egg had crash-landed on Angel Island, its impact having pushed the island into the sea. This sight made Knuckles recall a prophecy depicted on murals in the Hidden Palace Zone that said that a dragon would bring disaster to the island.
Over the next few days, Knuckles patrolled the island while looking for the Chaos Emeralds, where he met Doctor Eggman. Robotnik told him he was conducting research on the Death Egg to prevent disaster and that two people, named Sonic and Tails, were coming to steal the Master Emerald. Due to his seclusion, Knuckles believed Robotnik and made it his goal to stop Sonic and Tails and keep them from Robotnik, not realizing that he was being used by Robotnik to keep the duo at bay while he rebuilt the Death Egg.
When Sonic arrived on the island as Super Sonic with Tails, Knuckles pulled a cheap shot on Sonic that forced the Chaos Emeralds out of him, which Knuckles escaped with and hid away. As Sonic and Tails traveled across Angel Island, Knuckles attempted to stop the duo in Angel Island Zone, Hydrocity Zone, Carnival Night Zone and Launch Base Zone with his traps. As Sonic tried to board the Death Egg, Knuckles kept Sonic from getting close until tremors caused him to fall.
Sonic & Knuckles
After the Death Egg crash-landed on Angel Island again, Knuckles briefly visited the Hidden Palace Zone through a Giant Ring in Mushroom Hill Zone. After securing the hidden object (unaware that Sonic and Tails were watching), Knuckles disappeared into the forest.
As Sonic and Tails continued to explore the island, Knuckles opposed them with traps in Mushroom Hill Zone and Lava Reef Zone. However, as Sonic and Tails arrived in the Hidden Palace Zone, Knuckles faced Sonic in an epic showdown but lost. After his defeat, Knuckles heard an explosion at the Master Emerald's shrine and discovered that Robotnik was stealing the Master Emerald to power the Death Egg. Realizing he had been deceived, Knuckles tried to stop Robotnik but was electrocuted as the doctor escaped. Befriending Sonic and Tails, Knuckles guided them to Sky Sanctuary Zone from where they could board the newly-upgraded Death Egg II, though he was too exhausted to accompany them. Fortunately, Sonic and Tails returned with the Master Emerald to Angel Island, and Knuckles watched as his new friends and allies left the island in the Tornado.
Unfortunately for Knuckles, the peace came to a halt when an Eggrobo, under orders from Robotnik to eliminate Knuckles, attacked him with a bomb as he was relaxing in Mushroom Hill Zone. Through luck or toughness, Knuckles survived the explosion and set off to defeat Eggrobo. Knuckles followed Eggrobo to Sky Sanctuary Zone where it grabbed him with its Egg Mobile and brought it before Mecha Sonic, who had stolen the Master Emerald, threatening to make Angel Island fall once more. However, Knuckles escaped the Egg Mobile before Mecha Sonic could kill him, resulting in Eggrobo's destruction. As Knuckles fought Mecha Sonic, the robot used the Master Emerald to enter his Super State. Though Knuckles beat it, the fight caused their arena to crumble. Fortunately, Knuckles and the Master Emerald were rescued by Sonic in the Tornado, and the two returned to Angel Island with the Master Emerald. Having saved Angel Island again, Knuckles and Sonic departed ways once more.
A few months after the fall of Mecha Sonic, Knuckles noticed a new island had risen from the southern ocean as a result of tectonic activity simulated by the Master Emerald's presence when Angel Island sank into the sea, and was now rapidly flourishing due to the Master Emerald's pillar. Curious, Knuckles speculated it held the remains of the Knuckles Clan and that something there was amplifying the power of the Master Emerald's pillar. Duty-bound, Knuckles left to investigate the island. When he got there, Knuckles noticed that it had been converted into Newtrogic High Zone by Doctor Eggman, who sought to synthesize Dark Rings to help him steal the Master Emerald. Knuckles soon found Robotnik and made him flee with Metal Sonic as he was trapping Espio the Chameleon in his Combi Catcher. Knuckles then freed Espio, and they teamed up to free Robotnik's other captives and thwart the doctor's plans.
Together, Knuckles and Espio freed the captives Vector the Crocodile, Charmy Bee and Mighty the Armadillo, who also joined them, forming the Chaotix. Having collected the prestigious Chaos Rings, Knuckles and his crew stopped Robotnik's usage of the Dark Rings on several occasions. In the final showdown, the team was attacked by Metal Sonic, though the resulting battle made them fall into another room where Knuckles and the others were attacked by Metal Sonic Kai, a corrupted transformation of Metal Sonic and Robotnik's final trump card. Regardless, Knuckles and the Chaotix defeated it, restoring peace to the island.
Sonic the Fighters
Some months after peace was restored to the island, Doctor Eggman built the Death Egg III from where he planned to conquer Earth with his robots. To face this threat, Knuckles entered a fighting tournament where the winner got to collect all the Chaos Emeralds that belonged to the other participants, himself included. This would earn him the right to use the Emeralds for Tails' single-seat Lunar Fox and travel to the Death Egg II and destroy it. At the end of the tournament, the victor, likely Sonic, used the Chaos Emeralds to go to the Death Egg III and made it self-destruct moments after escaping it.
Sonic: The Ruby Saga
Main article: Sonic: The Ruby Saga