Karis was a Nightsister who lived with Mother Talzin and other Nightsisters on Dathomir. She appeared in four episodes of The Clone Wars and was mentioned in the novel Dark Disciple.
You can learn a bit more about the Nightsisters in this article from StarWars.com.
Catherine Taber, who voiced Padmé in The Clone Wars, voiced Karis in The Clone Wars.
In the clip below from “Nightsisters” Karis, along with Ventress and Naa’leth, attempt to assassinate Count Dooku.
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