XJ-6 is one of the prototype XJ robot sisters created by Nora Wakeman.
XJ-6 is tall and thin, with green pigtails similar to Jenny's, except straighter, pointier, and more triangular, facing forward, and three insect-like legs that bend outward at the ends. She has only one arm. She has a computer monitor-like head which displays her face on its screen, with one green eye (she is occasionally seen with two eyes), and a jagged mouth which resembles an electrocardiograph’s readings.
XJ-6 is often subject to dishonesty, as she easily gets jealous, especially toward Jenny, seeing as she is the one saving Tremorton instead of her and her earlier sisters. This has been mostly demonstrated in Turncoats. She even becomes jealous when bad things happen to those other than herself, as shown in Sister Sledgehammer, when she was not the first to be absorbed by the Cluster-possessed Jenny.
Sister Sledgehammer. She had to rescue Jenny from the Cluster, along with the rest of her sisters, but XJ-6 became the third to be absorbed by the Cluster-possessed Jenny (which she questioned "What? I'm not good enough to be absorbed first?") but is later freed.
Escape from Cluster Prime (Brief Cameo)
Labor Day (Brief Cameo)
XJ-6 (to Jenny): "Well, if it isn't Mother's favorite!"
Jenny (to XJ-6): "Alright, XJ-6, who's controlling you?"
XJ-6 (to Jenny): "Oh, why do you want to know? So you can stop it and save the day? Is always XJ-9 the big hero? And what are the rest of us? Chopped leavers?
-XJ-6 expressing her jealously about Jenny in "Turncoats".
- XJ-6's envious personality and design are a reference to the "Green Eyed Monster", mentioned in Shakespeare's quote: "O, beware, my lord, of jealousy; It is the green-ey'd monster, which doth mock..."