Señor Senior, Junior is a vain man-child with little to no interest in being a villain. While he generally goes along with his father's evil plans and has even attempted a couple jobs himself, he is usually too busy maintaining his tan and becoming a pop star to concern himself with world domination schemes.
Junior's first appearance is in the episode "The New Ron".
He was voiced by Nestor Carbonell.
Junior and his dad live on a fairly intimidating private island, somewhere off the coast of Europe. Kim first encountered them when Junior's giant tanning lamp was causing rolling blackouts across Western Europe. Upon going to their island and realizing that Senior didn't mean any harm, she gave him a lecture about energy conservation and let him be.
Unfortunately, during that same encounter, Ron commented that several features of Senior's island bore strong resemblance to a villainous lair, and gave him more suggestions for making his home more villain-worthy (Spinning tops of doom, self-activating lasers, speedboat for quick escapes, etc.). Senior originally dismisses Ron's suggestions, saying that they sound too sinister, but upon reflection, he decides that he needs a new hobby, and pretty much drags poor Junior along for the ride for the rest of the series.
However, Junior did show himself to have some potential for evil, as well. In the episode "Two to Tutor," Senior hires Shego to be Junior's tutor and teach him the ways of being a villain. Indeed, in learning how to be a villain, not only does Junior reveal how highly skilled he can be as a fighter, but he also shows a keen mind for developing evil schemes and outwitting heroes and good guys. Although Senior eventually breaks up the student/teacher relationship between Shego and Junior due to his jealousy of how much time his son is spending with her, Junior manages to retain at least some of what Shego has taught him in later episodes.
In the episode "Homecoming Upset," Junior, after breaking Shego out of prison, attempts to find the girl of his dreams, "the right combo of shallow, selfish, and insensitive, but still hot enough" in a girl. He hired a person named Ricky Rotiffle to use his special grid, but later finds one in Bonnie Rockwaller, who starts to develop some feelings for him. As a result of this, Junior gives up what little evil he did have to pursue his new relationship with her.
In the series finale episode, "Graduation," Bonnie is upset to learn that she need to undergo summer school after blowing her chance of receiving extra credit needed to graduate. However, Junior, who attended the ceremony, cheers her up by that saying that his heart will still be hers as she finishes up summer school, much to her delight.
Junior is, for the most part, interested only in himself. If he put his mind to it, he would likely be a better villain than his father, as he favors simple solutions over more complex "traditional" schemes (as shown in "Two to Tutor"). The problem is that he is extremely lazy. His dream is to become a pop star, although it is shown in several episodes that he has no musical talent.
Junior wears a tight yellow t-shirt with a red belt and tight black pants.
- Junior is one of only three Kim Possible villains who hates Ron more than he does Kim, and can thus be considered more his enemy than hers. The other two with this distinction are Monkey Fist and Gil Moss.