Kinniku Ataru (キン肉アタル, Kinniku Ataru) is a character from Yudetamago's manga and anime series Kinnikuman and its sequel Kinnikuman Nisei. He is the elder brother of Suguru Kinniku and the uncle of Mantaro Kinniku.
Ataru is the older brother of Kinniku Suguru, the protagonist of the series, and the eldest son of the Royal Kinniku Family.
In his childhood he could not endure the strict Spartan-like training his parents put him through and ran away from home. Because this all happened before Suguru's birth, Suguru was never aware of Ataru's existence.
Ataru watched over his little brother from the shadows as he fought against Evil Chojin, making sure he learned the value of friendship, and then returned after 25 years during the Survivor Match for the Kinniku Throne Arc.
As an experienced older chojin, he is viewed as an older brother to not only Suguru but the other Idol Chojin as well.
Ataru possesses what he refers to as True Friendship Power (真・友情パワー, Shin Yuujou Pawaa) and his own Kajiba no Kuso Djikara prototype called Gouka no Kuso Djikara (業火のクソ力, Fiery Inner Strength) (Ganso Kajiba no Kuso Djikara (元祖・火事場のクソ力, Original Burning Inner Strength) in the anime).
Ataru was born the eldest son of the Royal Kinniku Family and was first in line to become the next king of Planet Kinniku. But Ataru grew tired of their life of constant training, and left home to let his brother grow up to be the next ruler of planet Kinniku. Throughout Kinnikuman's career as a Justice Chojin, Ataru was watching him, hoping he would learn the value of friendship.
Eventually, Kinnikuman had proved himself worthy to inherit the throne after winning numerous championships and defeating many powerful Akugyo Chojin. However, five other "Kinnikuman" came forward claiming to be the true heir to the throne of planet Kinniku--they had all been born in the same hospital, and because of a fire they had been mixed up so the true heir might have been misplaced in the chaos. In truth, they had been chosen as the Five Fated Princes by five evil gods who feared Kinnikuman's power should he assume the throne. A survivor series tournament was organised to determine the true ruler.
Ataru went to Fujiyama and killed one of the Princes, Kinnikuman Soldier (キン肉マンソルジャー), who'd been selected by the God of Brutality, and stole his mask to be able to compete and help his younger brother prevail. He asked Buffaloman, Brocken Jr. Ashuraman, and The Ninja) to join his team, but they refused until they saw him save a little boy from an akugyo chojin.
However, Asuraman and The Ninja weren't fully convinced.
The Secret Story of the Chojin Blood Oath Brigade's Formation one-shot covers how Ataru convinces the Devil Knights to join his side. Soldier holds a secret meeting with his possible team mates. He doesn't intervene until Asuraman and The Ninja threaten to leave the meeting. When The Ninja attempts to read Ataru's mind with his Expose the Heart jutsu, there's nothing to read. Unlike the other Fated Princes, Ataru has no ambition to destroy his opponents and take over the throne. 
Asuraman gets into a fight against Ataru, but Ataru easily fends him off. Ataru even escapes the Asura Buster in a similar fashion to Kinnikuman and counters with a Dragon Cube Suplex. Buffaloman deduces why Soldier would pick those four. Pride is their main characteristic. According to Asuraman, "all four chojin are bull headed guys who won't listen to anyone". 
Asuraman asks if Ataru is a fake Kinnikuman Soldier and Soldier confirms this theory. He ambushed the real Soldier's team while they were training near Mt. Fuji and stole the real Soldier's mask. Ataru explains that he joined the tournament because the Friendship Power the Justice Chojin use is a sham and that the pride that they share can bring out their true strength. 
Asuraman wants Ataru to prove why this team of outcasts would make an excellent team. Soldier tells him to be silent. A real man would never talk so much. Instead, he'd silently watch the result with his own eyes. Asuraman follows up with his Tornado Hell, but Soldier dodges, causing the building already worn down by the Rolling Cube Suplex to collapse on top of them. Soldier heals them all with a Face Flash and makes a pact with the four Chojin. 
Calling themselves the Choujin Blood Oath Brigade (超人血盟軍, Choujin Ketsumeigun), they were given a buy into the second round and headed for Nagoya Castle, where they were pitted against Team Phoenix. After both The Ninja and Asuraman lost to Satan Cross, Ataru, Brocken, and Buffaloman met Kinnikuman Super Phoenix, Prisman, and Mammothman in a six-man tag match. The match took place in a floating cube with three separate rings on it.
During the match Ataru used the Face Flash and Niku Curtain, causing Mayumi and Sayuri to figure out his identity. He also spoke to Suguru of True Friendship Power. Brocken and Buffaloman managed to take Phoenix's allies out of the match at the cost of their lives, causing Ataru to hit Phoenix with a fury of his teammate's techniques. However, Super Phoenix tore Ataru's page out of the Muscle Prophecy Book and had Mammothman burn it. While disappearing, Ataru used a Muscle Spark on Super Phoenix to show his brother a move powerful enough to defeat Super Phoenix. Super Phoenix quickly regained the upper hand and defeated Ataru with his Muscle Revenger, and Ataru fell to the ground and disappeared.
Neptuneman gathered Ataru's ashes and used them to save Geronimo from being killed by The Omegaman's Omega Catastrophe Drop. The ashes appeared again and held up a flag to catch Bibinba when she threw herself from the stands. Ataru's spirit, along with those of Robin Mask, Neptuneman, and Geronimo appeared during Suguru's match with Super Phoenix and restored his Kajiba no Kuso Chikara (Burning Inner Strength) to him. Ataru and the others were restored to life when Kinnikuman used his Face Flash following his victory over Super Phoenix.
True Akuma Chojin Arc
Ataru makes his debut in this arc when he stole the Kinnikuman Soldier mask from the Chojin museum. He was asked to stop the Six Spears by the God of Brutality.
Like Super Phoenix before him, Ataru thinks that the Six Spears are being used by Satan. To make things easier, Omegaman Aristera suggests that there should be a tag-team match between the Omega Glorious (Aristera and Mariquitaman), Kinnikuman and Ataru.
He refuses the offer because Suguru was wounded terribly during his fight against Pirateman. Instead, Ataru uses the God of Brutality's power to destroy the barriers sealing away the three factions and picks a tag partner from one of the three factions. Brocken Jr. is Ataru's pick because Brocken Jr. was the only one who understood Ataru as much as Suguru. This tag-team is known as the Full Metal Jackets.
Aristera doubts Brocken Jr.'s capabilities and asks Ataru why he picked Brocken Jr. over the likes of Buffaloman, Asuraman, and The Ninja. Ataru stands by his choice. He even asks Aristera if he's truly prepared to fight against them.
Super Phoenix wakes up and reveals that he still has the remote for the six-way Anti-Gravity match from the Scramble for the Throne tournament. Aristera doesn't think the arena is still functional, but Super Phoenix says it reacts to a strong desire to wrestle and that it's ready to activate. Super Phoenix activates the arena, giving the Full Metal Jackets and the Six Spears a suitable ring to fight in.
The Universal Chojin Committee will preside over this match. The match starts off a bit rough for Brocken Jr. Mariquitaman seems to dominate him as he could counter his beloved Red Rain of Berlin technique. After that barrage, Brocken reminds himself that he's Kinnikuman Soldier's best choice and that he won't let him and his teammates down. Ataru pulls Brocken Jr. aside and gives him a dope slap, giving Brocken Jr. the motivation to fight back.
Mariquitaman's Rorschach Dot technique reveals an outline of Ataru's mask. Basically, Brocken Jr.'s deepest regret is being unable to do anything on his own. Brocken Jr. refutes that and shows off the Battlefield Dropkick combination attack on Mariquitaman. Ataru follows up with the Drill-A-Hole Cannon Driver technique.
Ataru baits out Aristera, which is good for Aristera. Aristera wants to see Ataru's Burning Inner Strength. Despite their deadlock in grappling strength, Ataru places Aristera into a Grenade Suplex. Ataru even manages to block Aristera's Four Finger Splash with a Niku Curtain guard.
Eventually, Aristera breaks the Niku Curtain and brags about his Chojin Strength given to him by the people of Omega Centauri. After demanding to see the Burning Inner Strength, Aristera places Ataru into a Powerbomb. Ataru reverses the move and counters a brand-new Niku Suppression. Ataru explains that the Kinniku clan's power doesn't just come from the Burning Inner Strength. It comes from the "righteous wrestling used by kings and based on solid moves and techniques".
In fact, Ataru will be glad to teach Aristera those techniques. Aristera retorts that Ataru abandoned his family and goes for a big boot kick. Ataru grabs Aristera and puts him into the Niku Downpour technique. Ataru and Aristera charge at each other, but Aristera slips out of the way. Mariquitaman does a powerful Tiger Feint Kick. Aristera isn't here for Ataru's mastery of wrestling techniques. He wants to see Ataru's Burning Inner Strength! The Omega Gloriouses place Ataru into a variant of the Mariquita Pupa Two-Fold Kill, the Glorious Sanction Crash.
After encouraging Brocken Jr. to fight back, Ataru steps in and invokes the Hellfire Inner Strength. He proceeds to do a Dragon Cube Suplex on Aristera. Mariquitaman intervenes, but Ataru swats him aside. After climbing back into the ring, Aristera reveals his backstory to Ataru. Before he became leader of the Six Spears, Aristera was considered an outcast until he learned about his special ability. Aristera is a mutant with the special ability of connecting and gaining an opponent's Chojin Power.
Receiving a beating from Ataru, Aristera achieves Omega Inner Strength and reverses Ataru's Napalm Stretch. He turns the match around and devastates Ataru with a Gigantic Glove Cutter. Ataru calmly states Aristera's Omega Inner Strength is filled with hatred towards The Man, so it isn't as strong as Ataru's Hellfire Inner Strength. Angered by this, Aristera beats down Ataru some more and delivers a speech on how Ataru is a thoughtless drifter who ran away from his family and his royal duties. Aristera fights for his people, unlike Ataru who does whatever he wants.
Even though the Omega Gloriouses display rather brutal techniques on the Full Metal Jackets, they still manage to stand because of Friendship Power. When Mariquitaman uses his Rorscharch Dot technique on Brocken Jr., the dots form the letter L, a sign that Ataru believes that Brocken Jr. should never give up in the face of adversity. Mariquitaman doesn't understand the meaning behind it until Brocken Jr. explains it for him. Mariquitaman thinks that means the L stands for defeat, but Brocken Jr. corrects him.
Brocken Jr. brings up his former grudge against Ramenman and compares that grudge to Aristera's grudge towards The Man. Living with a grudge like that will rob a man of their future. Brocken Jr. reverses the combination technique, pulling off a Double German Suplex. When Mariquitaman tries to cut up Brocken Jr. with his wings, Brocken Jr. counters with a Red Rain of Berlin technique and slices off Mariquitaman's wing.
Brocken gets on the receiving end of a Brains Shutdown Bomber, yet he still stands strong. Brocken Jr. boasts that Kinnikuman Soldier brings out the best in him. The Omega Gloriouses attempt another Glorious Graveyard Splash, but Ataru interrupts it, pulling off tag-team version of the Napalm Stretch, the Napalm Combination.
Aristera is forced to acknowledge he is now helpless. Ataru announces that he'll beat Aristera, but Aristera proclaims that Ataru understands nothing and unleashes a beating while listing everything that he lost in his fight to obtain Friendship Power. His losses didn't matter as long as he can keep fighting. Just as Aristera is about to pull off his Omega Armageddon Avenger, Ataru reverses it and claims that Aristera's "Inner Fire" needs to be stoked in order for the two fighters to understand each other.
In Nisei, Ataru has no known offspring and has been gone from Planet Kinniku for awhile, having formed the team of the Chojin Untouchables (超人警察隊) with The Ninja. He first appears in disguise, but reveals himself when he prevents Mantaro Kinniku from leaving the Superhuman Council Assembly Hall.  He incapacitates Mantaro by applying pressure to a vital pressure point, and he issues to Mantaro "the Fire Challenge", which will see him able to light the Lantern of Soul aflame. Ataru met Mantaro once when he was born, but left the planet and never saw Mantaro again afterwards.  Ataru then forces him into the challenge, although he after provides some comfort to Suguru. 
- Napalm Stretch (ナパーム・ストレッチ)
- Ataru leaps into the air with his opponent. He does a Romero Special and slams his opponent into the canvas. If Ataru leaps high enough with his opponent, the air friction is so bad, it can carve the letter "A" (An "X" in the Scramble for the Throne anime) into his opponent.
- Ataru's Muscle Spark (アタル版マッスル・スパーク, Ataru-ban Massuru Spaaku)
- Face Flash (フェイス・フラッシュ)
- Ataru takes off his mask, creating a blinding light on his opponent.
- Niku Curtain (肉のカーテン, Niku no Kaaten)
- Ataru raises his arms in a reverse V formation in order to guard against enemy attacks.
- Dragon Suplex (ドラゴン・スープレックス)
- Jungyaku Jizai no Jutsu (順逆自在の術)
- Borrowed from The Ninja.
- Choujin Lightning Strike (超人稲綱落とし, Choujin Izuna Otoshi)
- Borrowed from Ashuraman.
- Red Rain of Berlin (ベルリンの赤い雨, Berurin no Akai Ame)
- Borrowed from Brocken Jr..
- Buffalo Hammer (バッファロー・ハンマー)
- Ataru borrows one of Buffaloman's arm gauntlets and does a lariat with it.
- Battlefield Dropkick
- Ataru and Brocken Jr. leap off the ring ropes and do a double divekick on the opponent's back.
- Drill-A-Hole Cannon Driver
- Ataru grabs his opponent and crosses their arms. He proceeds to slam them into the ground, face first, while Brocken Jr. stomps on the feet for added damage.
- Grenade Suplex
- Ataru grabs onto his opponent's arms and locks them down. While his opponent is stuck in the arm lock, he does a mighty suplex.
- Niku Suppression
- A follow-up submission hold to his flying head scissors throw move.
- Niku Downpour
- Ataru grapples his opponent's leg and suplexes them into the canvas.
- Napalm Combination
- Ataru does a Napalm Stretch, but Brocken Jr. assists with the process. The move carves in the first initial for both of their first names and impales the opponent on the turnbuckle.
- 1st Kinnikuman Nisei Popularity Contest(9th place)
- 1st Kinnikuman Nisei ~All Chojin Dai Shingeki~ Popularity Contest (15th Place)
- Chojin Blood Brigade: Captain
- Eldest Son of the Royal Kinniku Family
- Chojin Untouchables
- Full Metal Jackets
- Fighting Devil (戦鬼, Senki)
- Win/Loss Record (Singles)
- O Woolman (Napalm Stretch)
- O The God Shark (Napalm Stretch)
- O Bulldozerman (Napalm Stretch)
- O Heavy Metal (Napalm Stretch)
- O Kinnikuman Soldier (Napalm Stretch)
- O Bockman (Napalm Stretch)
- X Kinnikuman Super Phoenix (Muscle Revenger→ Prophecy Page Burnt)
- As his brother Suguru was named after Yomiuri Giants player Suguru Egawa, Ataru's given name comes from Egawa's older brother Ataru.
- His age was originally given as 29, which would make him 5 years older than his Suguru, even though flashbacks showed him to have been at least in his late teens when Suguru was a baby. His age was later changed to 34 to fix that.
- In the English Dub, he is known as Sergeant Muscle
- He is left-handed