Red Raven can refer to either of two villainous characters, both tied to Raven; a crimson-clad Emoticlone embodying Raven's dark side, or a malevolent alternate version from a parallel universe who leads a supervillain team dubbed the Teen Tyrants.
Red Raven (Emoticlone)[]
The Red Raven Emoticlone is the mental embodiment of Raven's inner rage, hatred, anger, pure darkness and evil essence inside of her, the inter-dimensional demonic heritage from her malevolent father. Unlike the other Emoticlones, the Red Version possesses a far darker voice and four gleaming bright red glowing eyes (Though in the comics, she had two for a brief moment).
Out of all of Raven's Emoticlones, her most dangerous one is the Red Version; because of this, Raven must keep her constantly suppressed through intense meditation, for even the slightest expression of this emotion (such as in her battle with Doctor Light in "Nevermore" and Terra in the two-part second season finale "Aftershock") can cause her to go out of control and become much more demonic like her evil demonic father. When this dark form is manifested, Raven's supernatural, mystical abilities and powers are at their strongest and most powerful.

Rage in the shape of Trigon.
During the events of "Nevermore", her Red Version had escaped from Raven's control and was causing great mayhem throughout her mind in the form of Trigon. But thanks to some advice from Beast Boy and Cyborg, Raven fused with her other Emoticlones and went into her White Version, causing her to once again gain control of her.
Rage later returned in the Teen Titans Go! comic book issue Red Raven (a sequel of "Pieces of Me"), where she escaped into the world and began destroying anything and everything that seemed related to the term "Father," such as the Founding Fathers exhibit at the museum and Father's Day items in stores. This indicates that Raven hates her Red Version so much, even after she banished her, that she wants to cut off all ties with her for good.
Red Raven (Teen Tyrants)[]
This Red Raven is a parallel universe version of Raven who, rather than resisting the influence of Trigon, chose instead to embrace evil and become a supervillain. She is the leader of the Teen Tyrants, her reality's malevolent version of the Teen Titans, who function as a supervillain cabal out to dominate their world's version of Jump City. This iteration of Red Raven is confident, outgoing and in control; she is neither the rage-driven beast of her Emoticlone counterpart, nor compelled to control her emotions at all times like the real Raven. She and her universe's version of Robin, Red Robin, seem to be in a relationship, as the two refer to each other as "lover".
Compared to her counterparts, she has a slightly "punk-like" appearance, thanks to the magenta markings on her cheeks and elaborate black eyeliner design around her eyes. She wears a variant on Raven's outfit, with a magenta hooded robe (matching her magneta-colored hair and eyes) over a crimson-tinted black leotard; the difference is that Red Raven wears knee-high boots (compared to Raven's "pixie shoes") and a belt consisting of a single circular shape as opposed to Raven's multiple circles.
Her powers seem to be those of Raven, except her psychic aura manifests as a dark crimson color as opposed to the pure black of Raven.
Red Raven makes her appearance in issue #48 of Teen Titans Go! after the Teen Titans capture Killowatt. She psychically interrogates him to prove the veracity of his claims of being from an alternate universe, which inspires her to open a portal to the world he came from so the Teen Tyrants can go plundering. She works her magic at the same time as Raven attempts to open her own portal to rescue Killowatt, leading to a battle between the teams. Red Raven briefly turns the fight in her favor by using her psychokinesis to capture Robin, Cyborg, Beast Boy and Starfire, but as she is gloating about enslaving her "sister" Raven and conquering their universe, she is betrayed when Blackfire reveals herself as the Brotherhood of Justice member Gemini in disguise and grants her teammates access to the room. Red Raven is swiftly taken down by a telepathic attack from the Brotherhood's version of Psimon, which gives the Teen Titans a chance to take Killowatt and flee.