Knuckles the Echidna (Paramount)

Knuckles is an anthropomorphic echidna with predominantly red fur that covers most of his body, a black and pointy nose on his peach-furred muzzle, a white crescent-shaped patch of fur on his chest, and purple eyes. His eyes in particular glow red whenever he utilizes his chaos energy-based powers. He also has seven dreadlock-like spines around the sides and back of his head, broad shoulders, and a medium-sized, tri-crooked tail.

For attire, Knuckles wears two large white boxing gloves with spikes attached to them. He also wears red and yellow mountain boots. Each has the top folded down to reveal a soft green interior. The soles are light gray and each possess a gray, hextuple-bolted plate on top. When he was much younger, Knuckles donned a wooden tribal mask with feathers on it that was shaped in the form of a skull. On his white gloves and white footwear, he wore grayed-out sports tape. Additionally, Knuckles wore green cuffs on his ankles and wrists, as well as a beaded necklace. On parts of his face, dreadlocks, masks, Knuckles wore some white paint.

Past
Hailing from Mobius, Knuckles was raised as a warrior amongst his tribe, the echidnas, an ancient order of heroes who had been feuding with the owls for centuries over the echidnas' Master Emerald, a weapon of ultimate power that the owls had hidden away somewhere. During his childhood, the echidnas managed to locate Longclaw, the last of the owl warriors, whom they prepared to go after to get her secrets on the Master Emerald. While Knuckles wished to join his tribe in their battle, his father told him to remain behind and await the true moment where he would honor his tribe. However, Knuckles' father and his tribe died on that very day, leaving Knuckles as the last of the echidnas.

From then on, Knuckles would spent his life searching the galaxy for Sonic the Hedgehog, the apprentice of Longclaw, whom he believed to the key to finding the Master Emerald.

Sonic the Hedgehog 2
Detecting a spike of Sonic's chaos energy on the Mushroom Planet, Knuckles and his band of alien scavengers went there to investigate. When the scavengers got there through a Ring however, they were taken out by traps set by Dr. Robotnik, who possessed a chaos energy-infused quill from Sonic. Stopping Robotnik from using their Ring to escape the Mushroom Planet, Knuckles approached Robotnik and demanded where he got Sonic's quill from. Explaining that he got from Earth, Robotnik offered to show Knuckles the way. The two then made a deal: Knuckles would get him off the Mushroom Planet and Robotnik would get him to Sonic.

Arriving in Green Hills, Montana, Robotnik led Knuckles to Sonic's house. After Robotnik got Sonic to open the front door, Knuckles stepped in when Sonic tried attacking Robotnik, and punched him through a wall. Unimpressed, Knuckles punched Sonic through another wall when he tried charging at him. As Knuckles criticized Sonic's lack of warrior skills, Sonic charged at him again with a spin attack, only for Knuckles to stop it and overpower Sonic before pinning him against a tree. Knuckles proceeded to proclaim his purpose to restore the Master Emerald to its rightful place, but Sonic had no idea of what he was talking about. Refusing to listening to Sonic's claim and his questions about how he knew about Longclaw, Knuckles prepared to finish Sonic, only for a police car driven by Tails to ram him into a shed. As Knuckles recovered, Sonic and Tails drove away in the car. Setting off in pursuit of the duo, Knuckles eventually caught up to them and began tearing the car apart. In response, Tails drove the car off a cliff, leaving Knuckles to jump off the car and latch onto the cliff face before hitting the ground while Tails flew away with Sonic.

As Knuckles scaled the cliff, he was surrounded by Robotnik's Badniks. Robotnik proceeded to inquire Knuckles about the Master Emerald, but Knuckles insisted that it did not concern him as they had no further use for each other. As Robotnik had his Badniks help Knuckles up from the cliff though, Knuckles was told by the doctor that he needed his help navigating Earth. Furthermore, he would help him find the Master Emerald so that he could kill Sonic with it. Seeing that Robotnik was suggesting an alliance, Knuckles was convinced of his commitment after they shook hands on their deal. Making their way to the Mean Bean Coffee Café, Knuckles met up with Robotnik's assistant, Agent Stone, upon their arrival. Despite a rocky introduction, Knuckles displayed his trust in Stone with a firm handshake. Not long after, Knuckles saw Robotnik and Stone intercept a text message between Sonic and Tom Wachowski. Though Knuckles deduced that Sonic had returned home to Green Hills from the message, Robotnik proved him wrong by tracing Sonic's call to eastern Siberia. After then crushing a hologram of Sonic, Knuckles headed out with Robotnik to intercept Sonic. As they left, Knuckles took notice of Robotnik's disloyalty when he decided to leave Stone behind for now.

When the pair and some Badniks found Sonic and Tails inside a mountain in an ancient owl temple where they had found a compass that could lead them to the Master Emerald, Knuckles prepared to fight Sonic again. However, Sonic made the temple cave in when redirecting a missile from Robotnik's Egg Mobile, trapping Knuckles under some rocks. After escaping the temple, Knuckles noticed that Sonic was snowboarding down the mountain on a makeshift snowboard from a destroyed Badnik, Knuckles smashed a Badnik and took a piece from it as well to give chase to Sonic on. Catching up to Sonic, Knuckles eventually managed to topple him and make him lose his Rings over a cliff. Sonic would then banter with Knuckles about how echidnas had a habit of ruining his life, only for Knuckles to tell him the opposite as he revealed his past to him. As Sonic then admitted that they both lost everything that day, with Sonic having lost Longclaw when that happened, Knuckles would lower his guard, only for Tails to bind him with one of his gadgets. Calling Sonic out for being a deceiver, Knuckles broke free. As Sonic then tried passing the compass over to Tails, only for Robotnik to snatch it and knock Tails unconscious with a pair of missiles, Knuckles flew away with Robotnik as an avalanche approached. Before leaving, however, Knuckles noticed how Sonic chose to tend to Tails over the compass and Robotnik's disdain towards loyalty.

Using a Ring, Knuckles and Robotnik traveled to an island hundreds of miles away from Hawaii. There, they found a recess to insert the compass into, which in turn revealed an undersea temple in front of them. Entering the temple, the pair found themselves inside a labyrinth filled to the brim with deadly traps. After barely avoiding a number of traps however, Robotnik used an reconnaissance Badnik to map out the labyrinth for them. Eventually arriving in the central chamber, Knuckles punched down a wall blocking their way and found the Master Emerald on an altar right in front of them. As Knuckles proclaimed pride in what he and Robotnik had accomplished together however, Sonic arrived on front of them and made his stand against Knuckles. Though he tried going after the Master Emerald at first, Knuckles intercepted him and two began a long fight with the balance of power constantly shifting between them. When Knuckles got him pinned down however, Sonic made Knuckles see that Robotnik was stealing the Master Emerald.

Furious, Knuckles called Robotnik out for betraying their friendship, only for Robotnik to mock Knuckles' gullibility and lack of foresight before grabbing the Master Emerald and disappearing in a flash of energy that destabilized the temple. As the temple began collapsing, Knuckles got pinned down by a stone column in the rising water, which ultimately caused his to lose consciousness. As Knuckles recovered, however, he found Sonic attempting to save him. Together, they got Knuckles free, who in turn saved Sonic when he almost drowned due to his inability to swim. Back on dry land, a depressed Knuckles refused to answer Sonic's question about why he saved him until Sonic provoked him into answering. Knuckles told Sonic that he was repaying him for saving him despite not understanding his tactics for doing so. Sonic replied that he just could not let him die, which Knuckles did not understand given their past conflicts. In return, Sonic told him that heroes take responsibility for others and not themselves, which Knuckles could see the wisdom in. As Tails then showed up in the Tornado, Sonic encouraged Knuckles to come along with them and stop Robotnik. While Knuckles wondered how Sonic could move past his losses, Sonic advised him to find new friends to help him through it like he did, which convinced Knuckles to join Sonic's team.

Using a Ring, Knuckles, Sonic, and Tails flew back to Green Hills in the Tornado, just in time to see Robotnik finish constructing the Giant Eggman Robot with the Master Emerald's power. Soon after though, Knuckles jumped off the plane to deal with Robotnik alone. Charging at the Giant Eggman Robot head-on, Knuckles hit its fist with his best attack, but it did no damage. Reconvening with Sonic and Tails on the Main Street, who had faced similar failures, Sonic convinced them to work together as a team against Robotnik. As the Giant Eggman Robot unleashed Badniks upon them, Knuckles and his team tried coming up with a plan. As they discussed finding the Giant Eggman Robot's weak spot, Sonic realized that he was Robotnik's weak spot: if he could get Robotnik's attention, Knuckles and Tails could sneak into the Giant Eggman Robot and get the Master Emerald back. Beginning their plan, Knuckles got carried onto the backside of the Giant Eggman Robot by Tails while Sonic lured it out of Green Hills. After then cutting a hole into the cockpit, Tails distracted Robotnik long enough for Knuckles to get into position and knock the Master Emerald out of Robotnik.

However, this caused the Giant Eggman Robot to shut down, resulting in Knuckles and Tails sliding out of the robot and landing on the ground hard, causing them to lose consciousness. After recovering, Knuckles watched as Sonic and the Wachowskis seemingly got crushed by the Giant Eggman Robot. However, Sonic saved them all by transforming into Super Sonic with the seven Chaos Emeralds that fell out of the shattered Master Emerald, before destroying the Giant Eggman Robot and defeating Robotnik. When Tails and the Wachowskis tried approaching Super Sonic, however, Knuckles warned them that Sonic had gone mad with power. However, he was proven wrong when Sonic conjured celebratory chili dogs, with one of them landing in Knuckles' face, and relinquished the Chaos Emeralds. As the others celebrated, Knuckles took the Master Emerald's shards and fused them back together, although he wondered what he should do now that his quest had been fulfilled. Following Tails' suggestion, Sonic had the three of them form a new order, like the owls and echidnas, to guard the Master Emerald, which Knuckles agreed to upon making their oath, sealing it with a power-bump.

Some time later, Knuckles had a baseball game with Sonic, Tails, Tom and Maddie, although Knuckles had trouble grasping the game. Regardless, he managed to have fun with the game, even though he made them lose their only ball. Afterwards, the group decided to go for ice cream.

Sonic the Hedgehog 2: The Official Movie Pre-Quill
Seeking Sonic the Hedgehog, as he was the key to restoring "what was lost", Knuckles would scour the galaxy for him using Rings, assured that he could find him on his own. His search eventually took him to a volcanic planet. There, Knuckles climbed a cliff, only for a volcanic eruption to make him lose his balance and fall into a ravine. Though Knuckles survived the fall, it left him greatly weakened. Immediately after, a group of "scavenger scum" emerged from a Ring, who chained him up with energy shackles and took him to Casino Night to fight in a gladiatorial arena against the establishment's champion: a giant alien monster. As the monster plucked Knuckles up by his shackles, Knuckles managed to break free, run up along the monster's arm, and take it out with a single decisive blow to one of its heads when he utilized his chaos energy. Afterwards, Knuckles was released and received a bag of Rings as his reward. Realizing now however that he may not be able to capture Sonic by himself, Knuckles approached the scavengers, who were good at finding things, and offered them Rings to come with him on his search for Sonic.

With their aid, Knuckles and the scavengers would track someone whom they believed to be Sonic across different worlds. Upon reaching Hill Top Zone however, they realized that they had hit a dead end by following the wrong target. Regardless, Knuckles had one more place in mind where they could find a lead.

Sonic Drone Home
One time, Knuckles and his team were entrusted to return some library books for Maddie, which Knuckles swore to return safely. On their way to the library however, Sonic took Knuckles and Tails on a detour to the Green Hills Junkyard in order to investigate some strange noises. After arriving there, Knuckles and his crew found Unit, a self-aware Badnik in the process of upgrading himself in order to conquer the world. When Knuckles made his presence known however, Unit fired lasers at him that destroyed Maddie's books. Disgruntled, Knuckles ignored Sonic's attempt to make a plan and charged at Unit, only for the Badnik to catch him in a refrigerator and eject him from the junkyard, which let to Knuckles getting stuck in a sign. Eventually though, Knuckles returned and smashed Unit's body to pieces with an ambush. However, Sonic and Tails told him that Unit was no longer evil. As Tails was allowed to keep Unit's core module, Knuckles had his doubts about Unit, who vowed to make him submit to his prose once he had master poetry. Taking this as a sign that Unit was still evil, Knuckles demanded justice for Maddie's books.