Caution: Potential spoilers ahead for the Boruto anime series
Which villainous ninja are part of the evil Kara organization in Boruto? The story of Naruto Uzumaki is blessed with a host of great antagonists, from the venomous Orochimaru to the scheming Madara Uchiha, but much of the story is dominated by the Akatsuki - a group of rogue shinobi intent on collecting the world's Tailed Beasts. Over the course of Naruto's second half, the heroes take down Akatsuki one-by-one, but in the Boruto sequel series, a second alliance of shady ninja with grand ambitions emerge. Under the name "Kara," this organization's origins stretch back to the very beginning of the Naruto timeline, laying in wait throughout the years for the right time to pounce.
As Kara's endgame draws closer, the good ninja of Konoha Village get wise to their new enemies. Sasuke Uchiha already suspected trouble was brewing, but it was Boruto who inadvertently revealed the existence of Kara when using his Karma markings in battle against Shojoji, the chief of the Mujina Bandits. The crime lord recognized the technique and cowered in fear, worried that Boruto was somehow attached to Kara. Obviously, Naruto's son was innocent, but Shojoji's words drew Konoha's attention to the existence of this new evil organization.
Since Kara has been operating in the shadows for so long, the group already boasts a powerful roster of core members (the Inners), as well as a network of spies and agents (the Outers) loosely affiliated with the organization. In the Boruto anime, Kara are only just beginning to reveal themselves, but in the manga series, the group has more or less been dealt with. Here are all of the known Kara members in Boruto.
Jigen
Jigen is the undisputed leader of Kara, ruling over his followers with an uncompromising brutality. The name "Jigen" actually belongs to a monk from ancient times, who serves as the vessel to Kara's true leader, Isshiki Otsutsuki. Arriving on Earth alongside Kaguya (since Otsutsuki always travel in pairs), Isshiki was betrayed and left to die, but managed to inhabit a nearby monk before fading completely. Jigen's goal since then has been to resurrect himself in a more fitting body via the Otsutsuki immortality trick known as Karma and, like Kaguya, use Earth to create a chakra fruit. Jigen has spent years cultivating the perfect vessel, purchasing and raising Kawaki for this very purpose.
In terms of power, Jigen is able to defeat the (admittedly rusty) pairing of Naruto and Sasuke while still in his restricted vessel form. Had Jigen been allowed to transfer his essence to Kawaki, his power would've been far beyond anything seen previously in the Naruto franchise. Like fellow Otsutsuki, Isshiki can use space-time jutsu, and possesses the Byakugan. However, his right eye contains a more unique power, allowing Jigen to shrink and regrow objects at will. In combination with his eye technique, Jigen throws black rods, which he can render so small as to be invisible, and restore them again at the last second for maximum impact. Isshiki has implanted his Jigen vessel with the abilities of Karma, allowing him to absorb chakra attack and power-up like other Karma users.
Kashin Koji
Kashin Koji immediately caught the eye with a strong visual similarity to Jiraiya, but the similarities didn't end there. Koji's chakra is recognized by Konoha's security system (the area Jigen has him patrol), he uses the Rasengan technique, and can also summon frogs. While many speculated this Kara member could be Jiraiya's illegitimate son (not exactly a far-fetched conclusion), Kashin Koji was eventually revealed as an artificial clone made from DNA that Jiraiya left behind after death. Koji was designed to embody the values, spirit and power of his ancestor, and take down Jigen from the inside, posing as a Kara member to learn more about the Otsutsuki and create an opportunity to strike.
Kashin Koji's skill set is extremely close to that of Jiraiya. The character has demonstrated Shadow Clones, the Rasengan, Sage Mode, fire and oil-based ninjutsu, and toad summons, all of which were commonly associated with the great Jiraiya in a bygone era. Unlike Jiraiya, Koji is also kitted out with advanced scientific ninja technology, arguably making him stronger than the Legendary Sannin who provided his genetic foundation. Kashin Koji's current status is unknown after being soundly defeated by Isshiki.
Amado
Amado holds a unique role within the Kara organization - not fighting, but acting as their head of scientific research and technology. Amado has been at the forefront of Jigen's attempts to curate the perfect vessel, and worked tirelessly to turn Kawaki into a fitting test subject. Amado is also responsible for infusing the various Kara members with technology, making him the most advanced scientific mind in the franchise, perhaps only second to Orochimaru. In the course of his duties, Amado has committed or been complicit in many atrocities, including fatal experiments on children, but his true goal was always to find a way of defeating Jigen, and Kashin Koji was created for this very purpose. Recognizing that time had run out, Amado eventually takes his knowledge to Konoha Village and places his trust in Naruto and Sasuke to finish off Jigen.
In addition to modifying the Inners, Amado has also created a small army of powerful robots to serve at Kara's side. Later, after making his way to Konoha, Amado displays an advanced knowledge of ninja techniques and knows how to counter them, despite not being a gifted shinobi himself. Boruto has not yet revealed where Amado initially came from, how the Jiraiya sample was obtained, or where his knowledge was obtained.
Delta
Fiery, sadistic and explosive, Delta proves just how formidable the Inners of Kara are during her battle against Naruto Uzumaki. While all of Jigen's underlings possess some degree of tech inside their bodies, Delta is entirely cybernetic and her whole body can be replaced in the event of defeat. Despite being somewhat rebellious, Delta is loyal to Kara, although Boruto is yet to reveal where the "original" body might've come from. No Kara member is noble in battle, but Delta hits a new low by attacking Naruto's young daughter during their fight.
The Delta vs. Naruto battle offers the best insight yet into Amado's technological enhancements. Her eyes can absorb chakra attacks, while also firing off strong blasts of her own. Delta's legs are rocket-powered to allow even greater speed, and she can transform their shape, growing her limbs to add force behind physical attacks. Delta also carries a drone within her back that can be used for reconnaissance, and after a defeat, the device carries Delta's mind away so it can be uploaded to a brand new body at Kara HQ. Despite her strength, Delta possesses a crippling weakness - Amado included a shut-down command in her programming.
Code
Very little is known about Code at present, but the flame-haired villain has already made a striking impression upon Naruto fans. Bearing artificial attachments to his face, Code claims to be stronger than Delta, but it's not known whether he genuinely does outrank her, or whether he's just grandstanding to the other Kara members. Code's primary duty appears to be guarding the Ten Tails in Kara's possession, and it's assumed that this villain is still alive in the Boruto story, potentially setting up a return further down the road.
Victor
The oldest of Jigen's followers (in appearance, at least), Victor barely features in the Boruto manga, where he's executed by his own people for failing a mission, but the anime has greatly expanded upon the character's backstory. Based in the Land of Valleys, Victor fought in the Fourth Great Shinobi War, but now owns a pharmaceutical company. Behind the scenes, Victor is an Inner of Kara, funding and serving Jigen, but his agenda is more selfish than simply following orders. Similar to Jigen, Victor seeks to revitalize his own aging, injured body, and goes rogue in an attempt to create his own God Tree from stolen fragments of Kaguya's - a plan that inevitably fails. In the Boruto anime, Victor works alongside a second Kara Inner named Deepa, but this is an anime-only creation.
Despite his age and deteriorating condition, Victor's abilities are worthy of his Kara membership. Owning a medical company, it's no surprise that Victor's best techniques involve regeneration, and the villain boasts one of the most potent healing jutsu seen in the Naruto franchise, growing body parts with minimal fuss, and even adding extra limbs in battle. As well as being fluent in all five nature releases, Victor carries a curse mark, similar to Sasuke in the original series. This helps to artificially sustain Victor's life until he can find a more permanent solution.
Boro
The bulkiest member of Kara, Boro comes to the fore when guarding the imprisoned Naruto Uzumaki against Boruto, Sarada, Mitsuki and Kawaki. Many of Boro's attacks are chemical in nature. He spits acid during battle, takes opponents by surprise with an immovable fog, and inflicts enemies with an immobilizing virus that he is inherently immune to. Like the other members of Kara, Boro can cheat death through Amado's futuristic technology, but his method for doing so is unique. Boro is able to shift his "true" self around his physical form, making it very difficult to land a killing blow. While Boro's consciousness is elsewhere, damaged body parts are then able to heal from even the most extreme injuries. While it's Sarada who manages to destroy Boro's elusive core with a well-placed combination of her father's Sharingan and Chidori, Boruto finishes off Boro after becoming possessed by Momoshiki.
The Outers
Ao - A Mist ninja introduced in the original Naruto series. Jaded by the peaceful modern world, Ao has been corrupted by the values of Kara, but remains merely on their periphery.
Garo - Garo is another disposable associate of Kara, and was injured during a fight with Kawaki in the past. Other Boruto anime-only Outers include a child from the Hidden Rain and Dr. Iwa.
Dr. Katasuke (unwillingly) - Konoha's head of scientific ninja research served Kara while under genjutsu, providing them with top-secret technology and data.