Senior usually wears a burgundy suit coat with a white cravat and some sort of blue shirt underneath, khaki slacks, and brown shoes. He has a tattoo of three S's on the back of his neck.
Senior is always extremely polite, even while he's trying to kill Kim. This goes beyond sarcastic or insincere flattery; it seems like he's just a genuinely nice person. He's also very involved in his son's life, to the point where he has trouble letting Junior plan a crime by himself. He also seems obsessed with traditional villainy, telling Junior at one point not to finish off Kim Possible so that she could have the chance to do something heroic.
Senior's only known family is his son, Señor Senior Junior. They appear to be fairly close, although Junior somewhat resents his father's focus on traditional villainy and would rather use their vast fortune to become a pop star.
Senior and his son 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 dismissed Ron's suggestions, saying that they sounded too sinister, but upon reflection, he decided that he needed a new hobby.
Senior does not work with other villains (other than his son, of course) and is less than pleased with Junior's occasional partnership with Shego.
He formerly belonged to a billionaire's club (He was ejected for fighting with an American cheerleader and losing. It seemed a bit "too weak-like"), and regularly has the four other richest people in the world (including Pop Pop Porter and Martin Smarty) over to play cards.
Talents and Skill
Senior's main asset is his outrageous personal fortune, which allows him to simply buy devices that other villains have to work to steal or build. While he's not much good in a physical fight (being an old man and all), it is revealed in the episode Triple S that he is incredibly good at extreme sports, and can apparently fight while skydiving
- Senior's first appearance is in the episode "The New Ron". His voice was originally provided by veteran Mexican actor Ricardo Montalban, but he's later voiced by Earl Boen after Montalban passed away.
- Senior is one of five richest man on the Earth.
- Weakness of the Senior are his passion for "villain traditions" and his extremely complex plans.
- Neither father nor son make an appearance in the Shego-controlled world seen in "A Stitch in Time". A possible explanation is that Senor Senior Senior is just too old in future (over 80 years) to challenge Shego for world domination. Another possibility is that he and/or Junior rule other parts of the world in Shego's name.