Ruby Knowby is the main villainess from Ash vs Evil Dead.
She is portrayed by Lucy Lawless of Xena: Warrior Princess fame.
Ruby Knowby is the daughter of Professor Raymond Knowby and the sister of Annie Knowby, both from Evil Dead 2. She has been searching for Ash Williams since their deaths, as she blames Ash for what happened to her father and sister and was planning to kill him.
Ruby briefly appeared in the series premiere "El Jefe", encountering detective Amanda Fisher after witnessing the demonic possession of her partner and having to kill him.
In "Brujo" Ruby saved Amanda from the demonically possessed Lionel, and then convinced Amanda that Ash was to blame for everything that has happened. She also convinced Amanda to help her hunt Ash down, and in the following episode "The Host", she revealed herself to be in possession of Ash's severed, possessed hand (which Ash cut off in Evil Dead 2), and was using it to track him down. They both arrive just a hair too late at the Brujo's ranch in "The Killer of Killers", which later saw Ruby engaged in a fight with the Brujo's charred skeleton, who tells Ruby that she'll never have possession of the Necromicon. They both fell in the exploding pyre, but Ruby emerged unscathed in the following episode "Fire in the Hole".
Ruby finally finds Ash in the season's penultimate episode, "Bound in Flesh", and confronts him by stating that she had been "cleaning up his mess." She shoots down Ash's plan to bury the Necromicon, stating that the book had to be destroyed. Back in the cabin where it all started, Ash defaces the cover of the book, and gives it to Ruby. However, Ruby opens the book and reads an incantation that will unleash all of the evil in the world, which included the face of the book attacking itself to Pablo's face. At that moment, Ruby reveals herself as the actual writer of the Necromicon, also revealing herself as a Dark One.
In the season finale "The Dark One", the evil Ruby attempts to convince Ash to give up his battle against evil, stating that she only wants to release all of the evil just to keep it under control. In return, she'll give Ash what he's always wanted, a normal life and a peaceful retirement in Jacksonville. After Ash refuses, Ruby roars at him, flashing a pair of demonic black eyes while doing so, and Ash is transferred out of his fantasy scene in his trailer, and back in the real world in the cellar of the cabin. Ruby and Ash fight once again, with Ash set to kill Ruby with the Kandarian dagger, which was used to deface the book. At that moment, Ruby makes the same deal she made before, and this time, Ash accepts, to the dismay of Pablo (now free from Ruby's control) and Kelly. However, while Ash, Pablo, and Kelly are driving away, a sinkhole is formed; an indication that Ruby hasn't been true to her word.