Jack Spicer is a self-proclaimed "Evil Boy Genius" and one of the main villains. He is constantly building different types of robots, the most common is the Jack-Bot.
Jack can easily be described as childish. He is spiteful and loves to gloat, which usually costs him his victory. He is cocky, especially at the beginning of the series, and is often a smart-alek. He is obnoxious, whiny, and dramatic. He is spoiled by his rich parents, but he is also determined. Despite his genius and technological prowess he is very clumsy and goofy, and has little common sense. He often uses dated and odd-sounding sayings and phrases, and is somewhat eccentric.
Jack has many fears, is easily frightened, and almost always panics when confronted; however he shows up to almost every conflict. He manages to put off everyone he encounters, with almost every character considering him irritating.