Ren Krawler (レン・クロウラー, Ren Kurourā?) is a Darkus Brawler from Gundalia and is also the last descendant of the Protectors of the Dark Bakugan to never allow Linehalt from unleashing his forbidden powers. He originally worked for Barodius thinking he could get his freedom. Later, he was exposed by Fabia, but later returns to the Battle Brawlers and became a Castle Knight. He went back home to Gundalia after the Neathian-Gundalian War ended. As of the events during Bakugan: Mechtanium Surge, he is currently the Commander of the Gundalian Forces under the commands of Prime Minister Nurzak.
Ren is a Gundalian disguised as a human. He was sent by Emperor Barodius to find the strongest brawlers to help defeat Neathia and to find the DNA Code. Ren comes from the underground world of Gundalia, where he was kept by Emperor Barodius' family because he possesses a Dark Bakugan with a very powerful ability (the Forbidden Power). He lies to the brawlers telling them that the Neathians love war and invaded Gundalia and that the Gundalians always want peace, when it's really the other way around. He probably gave the brawlers the newer Phantom Data in order to let the Gundalians pass into Bakugan Interspace detected as so-called "Neathians".
He looks artful, cruel, and he underestimates friendship at first, but after that, he began to show compassion by feeling sorry when a member of his team was punished for their losses, trying to save Sid from falling into the valley, and saving Marucho from being captured by a flesh-eating plant.
Ren starts off as a rather self-motivated person who, while he didn't oppose friendship, didn't view relationships very highly, aside from his bond with Linehalt. As the last descendant of the protectors of the Dark Bakugan, he and Linehalt were always forced to live underground. In order to attain freedom, Ren serves Barodius, with the mission of finding and recruiting brawlers for Gundalia's war against Neathia.
He starts off having rocky relationships with most of his teammates and the brawlers. While Marucho saw him as a friend due to the Phantom Data Ren gave him, Shun had no problem with exposing Ren's true purpose after hearing Fabia's side of the story, which hurt Marucho greatly. Ren's own teammates teased him when he forgot his mission due to his bond with the Battle Brawlers.
However, as the series progresses, he comes to value others more. While he didn't get along with Sid for most of the series, he tries to save Sid when Dharak attacks him, and Sid entrusts Ren with Rubanoid and Destrakon Gear before he chooses his own death. When he overhears about the disposal of his other teammates, he apologizes to them for their fate, especially in cases where he had taken part in the losing brawls that they were punished for.
After realizing that Barodius was just manipulating him, Ren loses his loyalty to him and turns to Neathia's side. However, he still respects his superior Nurzak, who also opposed Barodius' motives and actions. Even before betraying Barodius, he did not hold any grudges towards the Neathians and has displayed respect for them. Knowing that it would be better for a Pyrus brawler to use Sid's Bakugan, he entrusted Rubanoid to Linus Claude and seems to have become friends with him. He get along with Mason Brown and Jesse Glenn.
In A New Beginning, he gave them a bigger amount of Phantom Data, which allowed Marucho to make Bakugan Interspace available to everyone. He later battles Dan and Helix Dragonoid with his partner Linehalt. As the battle intensifies Dan is knocked out and has a vision of Bakugan at war. Everyone except Ren was surprised.
In Revelation, he tells the brawlers that he is from Gundalia and that the Neathians attacked them and that their Bakugan are trained to be soldiers (the Gundalians are the real culprits, not the Neathians). Upon Fabia Sheen's arrival, he tells her that he is a Gundalian. Then Shun asks Fabia for her side of the story.
In Confrontation, he brawled with Dan against Sid Arkale and Zenet Surrow. Though he does pretty well in the battle he purposely loses in the first and second round so Sid and Zenet could defeat Dan and get Drago. Although his plan works Sid chooses not to take Drago due to the battle being unfair. He is later seen conversing with Linehalt about their plan working.
In Exposed, he created a rift in the new battle arena because he thought that Dan was going to battle Jesse Glenn but it ended up that Fabia battled Jesse and the rift effected Aranaut. Shun exposes him to the brawlers after the battle and he denies everything and then runs off. Seeing as how Ren helped Marucho develop Bakugan Interspace and became good friends, he refuses to believe Ren is lying to them.
In True Colours, Ren loses to Marucho and then he said that they could still be friends if Marucho left the Brawlers but he said no. Ren also had trouble before that controlling his teammates and said that they couldn't just hypnotize the Brawlers because a hypnotized person only operates at seventy-five percent. He also said that any insubordination would result in him telling Emperor Barodius. Ren later reveals his true form. However, it is shown through their actions that Ren and Marucho may still care for each other, though in the end of the episode, Marucho was clearly upset at him for betraying the Battle Brawlers.
In Hostile Takeover, Ren leads the Gundalian brawlers to kidnap more children to brainwash into Gundalian soldiers. Dan confronts him, but Sid and Mason stay behind with two brawlers named Taylor and Casey to battle them. While they are battling, Ren secretly hacks into Interspace and forces the Battle Brawlers out. Afterward he tells them he is now in full control of Bakugan Interspace.
Ren's dark past was revealed in Escape From Darkness. As a child, he was forced to be Linehalt's protector. He was initially scared of Linehalt at first but eventually became close friends with him after Linehalt saved him from falling from a ledge. The two spent most of their time together training and sharpening their skills. As Ren got older he asked Linehalt if they would ever see sunshine in their lifetime. Under the illusion of fulfilling that wish, Emperor Barodius himself appointed him to lead a team to Earth. After finding out Marucho infiltrated Bakugan Interspace he confronted him. Marucho was willing to brawl Ren to determined who would leave Bakugan Interspace but then Ren revealed the outcome of Fabia's battle against Lena and Zenet, letting Marucho ran off to help Fabia.
In The Element, he and Kazarina are seen talking about a Bakugan belonging to a Castle Knight. Kazarina gets suspicious that this Bakugan might be the one who possesses the Element, so she orders Ren to bring it to Gundalia so that she may examine it. Despite his attempts to do so, Sid stole Neo Ziperator so that he could seek a grudge match against Dan. Left with no other choice, Ren was forced to simply watch the brawl and hope Sid could win. Ultimately however, Neo Ziperator passed the Element on to Lumino Dragonoid, putting it back in Neathian hands.
In Twin Evil, after hearing from Zenet that the Brawlers were going to Neathia, he ran to follow them but just when he arrived to the scene, the Brawlers had already escaped.
In Curtain Call, after figuring out that Jesse ran away in the middle of the night from Kazarina and Stoica, Ren goes to follow him. He then, tags with Jesse against Fabia and Jake, the result of the match ended in a loss. He then brings Jesse back to Gundalia, and watches him and his partner Plitheon perish before his eyes. Ren ultimately felt sorry seeing it happen, stating that he also took part in the battle that resulted in the loss, but Kazarina told Ren to speak to Emperor Barodius about it himself, showing little to no disdain for Jesse's apparent demise.
In The Secret of the Orb, he battles Fabia and Marucho alongside Nurzak. The battle ended in a tie due to the interruption of the Sacred Orb, which was presumably angered by Ren and Marucho (former friends) fighting against each other.
In Mobile Assault Kazarina asked Ren to bring more battlers from Earth, which the latter agree with her. Later in Bakugan Interspace, annoyed by Stoica complaining about why should he be here, Ren told him to just get in his human form. After that is done, Ren told him to they should go get battlers, but the latter retorts, saying that he prefer to look for battlers in their natural habitat. Linehalt did try to convince Ren to reconsider their loyalty to the Twelve Orders as they show them none.
In Sid Returns, he fights off against Dan and his new Mobile Assault Vehicle. Dan attempts to convinces him to switch sides, but he refuses. Just when things were looking bad for Ren, Sid suddenly appears and joins the fight. Despite the momentary two-on-one advantage, they end up losing. Sid then explains that he and the rest of Ren's team (minus Mason, who also escaped) weren't killed, but simply held in stasis in Kazarina's lab. Just then, Dharak shows up to punish Sid for escaping. He blasts Sid, who nearly falls in a ravine. Ren grabs his hand and attempts to pull him back to safety, however, Sid gives Ren Rubanoid and lets go, ultimately falling to his death.
In Colossus Dharak, he accompanied Barodius on a mission to permanently destroy the second shield. Dan fought against Barodius and lost, leaving Barodius to order Ren and Linehalt to finish him off. However, he turns against Barodius at the last second, having finally realized his master's true motives, and attacks him with Linehalt and Boomix.
In Dragonoid Colossus, he fights Barodius to protect Dan and the rest of the Brawlers. He manages to hold his own for a while, but suddenly Linehalt reveals his Forbidden Power which nearly destroys the planet. The Sacred Orb sends out Dragonoid Colossus in response, which defeats both Linehalt and Dharak before disappearing into Dan's Bakumeter. After the battle, he believes he needs to live in isolation because of the dangers of the Forbidden Power, but the Brawlers convince him to come back with them. He expressed happiness at their decision and transforms into his human form, although Fabia still appears skeptical of his intentions.
In Forgiveness, he is left behind on the battlefield by Fabia after returning to Neathia. When Marucho goes back to look for Ren he is nearly eaten by a carnivorous plant but Ren saves him. He then brings food for Marucho, and comments that he doesn't deserves his forgiveness. Marucho tries to convince him that he has already been forgiven by the Brawlers but Fabia appears, challenging him to a brawl. Ren battles against her to prove his new loyalty to the Neathians. He fights with Linehalt and loses, most likely due to Linehalt's exhaustion from having just used his Forbidden Power. Ren uses Rubanoid to compensate for Linehalt's weakness, but is still unable to win. After his loss, he is actually seen crying as he thinks he has failed Sid. Fabia then accepts him in despite her previous terms. Ren later becomes a fully-fledged Castle Knight despite being a Gundalian.
In Infiltrated, he declares that he wants to rescue his surviving former teammates from Kazarina's lab. He, Mason, Nurzak, and Fabia split off from the rest of the group to search for them. In the next episode, they split into two smaller groups and Ren is paired off with Mason to continue on his objective.
In Redemption, he and Mason finally reach the lab, only to find that Lena, Jesse, and Zenet have been removed from their stasis tubes. The two of them then meet up with Fabia and are surprised to see Nurzak and Sabator gone, leaving Fabia to explain that they were lost in a brawl with Stoica and Kazarina.
In Final Strike, he and Fabia reunite with Shun and Marucho, but not before mistakenly attacking them due to their disguises as Gundalian soldiers. The group goes to Nurzak's secret lair to meet with Mason. The Brawlers later launch an assault on Barodius' castle, and Ren stays behind to delay Gill.
In Dream Escape, he and Linehalt reunite with the other Brawlers and begin to battle the Twelve Orders.
In Gundalian Showdown, he battles the Twelve Orders with the other brawlers and manages to escape to Neathia on Dragonoid Colossus. It is also revealed that before he left to go to Gundalia, he entrusted Rubanoid to Linus, as he thought that Rubanoid would be better off with a Pyrus brawler.
In Broken Spell, he briefly battles the hypnotized Jesse and Plitheon until Kazarina's hypnosis breaks, and later joins his fellow brawlers and former teammates in a final showdown with the Gundalian army.
In Gundalia Under Fire, the Battle Brawlers returned to Gundalia to help him defend his home from the raiding Chaos Bakugan. It is revealed that he is now the Commander of the Gundalian Forces. He then tells them that Mag Mel invaded Gundalia and that he seems to be heading for the palace. Just then, Dan gets a vision that Mag Mel is heading through Dalia's Valey and Ren comments that the route would lead straight to the palace. Then Marucho decides to launch a sneak attack on Mag Mel. Unfortunately, Mag Mel reads Dan's mind and catches on to their plan. Mag Mel then makes quick work of everyone except for Dan and the two engage in a prolonged brawl. Ultimately, Mag Mel proves victorious against him as well. Later, Ren overhears some Gundalian soldiers discussing Dan's link to Mag Mel and wonder if they can really trust him, to which Ren scolds them, though he also secretly wonders the same thing.
In Battle Lines, he can be seen with the Battle Brawlers and Captain Elright discussing their next move. He watches in shock when Dan grabs Marucho by the collar. He then later tells Dan, Shun, and Marucho that Rafe and Paige have gone after Mag Mel.
In Unlocking the Gate he is first seen telling Linehalt not to let the Chaos Bakugan go through. After Dan defeats Mag Mel, he watches as all the Chaos Bakugan disappear.
He makes a brief appearance in The Final Takedown looking up at what is left of Gundalia's Dark Moon in a non-speaking cameo appearance.
Bakugan: Gundalian Invaders
- Darkus Linehalt (Guardian Bakugan)
- Silver Boomix (Battle Gear)
- Pyrus Rubanoid (Given by Sid before he died - Gave to Linus)
- Gold Destrakon Gear (Rubanoid's Battle Gear - Gave to Linus)
- He has a resemblance to the Beyblade: Metal Fusion character Ryuga, most notably their similar hair color and reptilian-like eyes. Also, the strange headband Ryuga wears looks very similar to Ren's forehead in his true form.
- He is the only one of the Minor Twelve Orders to have an Intermission Screen that shows their real form.
- He is the earliest of the six/seven antagonists to change sides in the series.
- Out of the three villains to swap sides, he is the only one without a mask. Instead, he uses something to change his entire appearance.
- Ren's name could possibly be reference to the Ren, a part of the soul in Egyptian mythology.
- He is the only minor character that appeared in three seasons; New Vestroia, Gundalian Invaders, and Mechtanium Surge.
- Ren's appearance and initial role in the story are similar to Vector's from Yu-Gi-Oh! Zexal II; both are posing as a friend of the main character, who in reality work for an opposing alien faction whose members disguise themselves as humans to blend in on Earth. Ren and Vector, in their true forms, also have similar color schemes. Hower, Vector (along with Don Thousand) end up being the main antagonists, whereas Ren eventually sides with the Brawlers.
- Ren is the only Gundalian to have been in 3 Bakugan TV series seasons; Season 2 to 4. (New Vestroia to Mechtanium Surge Arc 1)
- Ren Has spiky hair, like Grey's From Mega Man ZX Advent.
Ren has proven himself to be an excellent brawler but due to Ren facing the Battle Brawlers so often, his record is tarnished due to his losses against them.
Bakugan: Gundalian Invaders
|Castle knights (tag with the Twelve Orders)||Offscreen||Win|
|Dan Kuso||1||No Outcome|
|Sid Arkale and Zenet Surrow (Tag with Dan)||5||Lose (deliberately)|
|Shun Kazami and Linus Claude (Tag with Jesse)||11||Win|
|Fabia Sheen and Jake Vallory (Tag with Jesse)||18||Lose|
|Fabia Sheen and Marucho Marukura (Tag with Nurzak)||19||No Outcome|
|Dan Kuso (Tag with Sid)||23||Lose|
|Fabia Sheen||26||Lose (due to Linehalt being worn out, lost with Rubanoid)|
|Gill, Kazarina, Stoica, and Airzel (Tag with The Battle Brawlers)||36||Win|
|Jesse Glenn||37||No Outcome|
|Barodius, Stoica, and Airzel (Tag with The Battle Brawlers the Gundalian Agents (except sid) and The Castle Knights)||37-38||Lose|
Bakugan: Mechtanium Surge
|Mag Mel (Tag with Brawlers)||17||Lose|
|Chaos Bakugan Army (Tag with Castle Knights)||18-19||Win|