Indigo

Indigo is a Coluan previously known as Brainiac 8. She was deemed the most dangerous prisoner ever sentenced to Fort Rozz.

Fort Rozz
Brainiac 8 was imprisoned on Fort Rozz for attempted genocide on Krypton when it was trapped in the Phantom Zone. After years of searching, she eventually finds the Kara Zor-El pod. She takes over the pod, causing the young Kryptonian to wake abruptly, and notices a computer console in her dashboard with a logo with three dots in a triangular shape before Fort Rozz's engines activated and both escaped the Phantom Zone.

Indigo
Taking on the alias "Indigo", Brainiac 8 travels through the internet with the hopes of wiping out all Humans on Earth. She tries to release private information about an infidelity website (DiamondDiscretions.com) to Catco, but Cat Grant refused to release it. The monitors and other electronic devices start to go haywire at CatCo and the hacker (who was Indigo taking on a human face on-screen) tells Cat that since she ignored what was on the drive, there is going to be chaos in National City. She keeps to her word and all the lights in National City turn green, causing major car crashes. At Kara's apartment, Kara and James Olsen watch Winn Schott try to crack the hacker's code to no avail when the hacker appears on the screen and teleports through the computer into the room as a blue woman with the symbols of Brainiacs. She attacks Kara, and threatens to kill Winn and James Olsen, but Hank and Alex arrive and scare Indigo off. Later, Indigo teleports through another computer and meets with Non, where it's revealed that the two had earlier sexual encounters. Indigo tells Non that Astra’s notion of living alongside the humans can’t work, and says she'll do something to the human race so she and the Kryptonians will be only ones left on Earth. At the military site, Indigo uses General Mathers' cell phone as a means to enter the base. She swiftly kills/takes out the officers in the room, and reveals a stretching power to turn both activation keys. Kara arrives and fights Indigo. Indigo eventually traps her with her legs, but Kara escapes and goes after the missile. Realizing that anything she tries could destroy National City, she finally relents to consult Hank, who guides and helps Kara disarm the missile's tracking computer. Indigo, initially infuriated her initial plan failed, tries to send more missiles, but is knocked down by Kara. Kara dropped her phone during the landing (not seen on screen). After learning that Winn is working on a virus that will destroy her, Indigo uses the active device to reach Winn and choke him. Winn, though being strangled, continued to prepare his virus. Indigo begins to try to get Kara to back away, saying she (Indigo) is "invincible". Winn calls her a "glorified Windows Vista" and uploads the virus to Indigo. While she's being destroyed, she explains that if it weren't for her finding Kara's pod, none of them would have been on Earth at all. The virus finally consumes her, leaving no trace of her remnants.

Finally, Non, using the Omegahedron, shows that Indigo was not actually destroyed, with her body appearing on the computer board in severed pieces. Non says, "I merely broke your heart. Look what Supergirl did to you," and eventually says that he wants her to do things his way now.

Indigo was pulled apart by J'onn J'onzz in the season finale.

Powers

 * Cybernetic Interface: Brainiac 8 is a Coluan cybernetic being. She is able to transfer body in the form of digital code and teleport through any technology by flying into it while in digital form. She can use any electronics as a portal to another destination, traveling through electronic and digital signals, while she is unable to travel through older broadcasting signals. She also could teleport only part of her body if she willed it, as she teleported her arm through a phone's screen, causing it to teleport out from Winn's computer and choke him. She can interface with any machinery and manipulate computer systems, as well as detect digital electronics and signals, while she could not do so with older broadcasting signals and technology.
 * Super strength: Indigo has enhanced strength equal to that of a Kryptonian's.
 * Super speed: Indigo also showcased blinding levels of speed able to tackle Alex to the ground in an instant.
 * Invulnerability: Indigo's body is denser than a human's but not nearly as durable as a Kryptonian's.
 * Shapeshifting: Indigo can take the from of a blue athletic female or a blond human, the latter of which she only appeared as while projecting herself on computers or video screens. She is able to manipulate her limbs to stretch and elongate to almost no limit and turn her fingers into claw like blades. It is later revealed that she can turn her limbs into blades that can can pierce into Martians.
 * Self Repair: As a digital being, Indigo is able to self repair, though she only if she is conscious, otherwise the Omegahedron can be used to reconstitute her, as Non did.

Abilities

 * Expert hand-to-hand combatant: Indigo is an expert in unarmed combat. Combined with her raw physical power, she was able to physically restrain Supergirl from behind with a grappling maneuver.