Dexter (Voiced by Christine Cavanaugh, seasons 1 & 2 and Candi Milo: Seasons 3 & 4)

Dexter is a young boy genus who dedicates most of is free time in his secret Laboratory, always working on new inventions and often neglecting old ones as seen in "Lab of the Lost" he really enjoys school as well and is loved by many of the teachers, as seen in "Dexter's Rival", "Dexter Detention" and "Aye Aye Eyes"  Despite is love for working all the time, Dexter is still your regular little kid at times, he has enjoyment of ice cream, cartoons, action figures and video games.

Dexter had a few crushes on the series, including his babysitter, Lisa who is ten years older then him, more or less and a hot blonde girl named Candi who he tried to get to play his sister  in "Dee Dee and the Man"

While Dexter gets angered to no end with his sister Dee Dee destroying his lab and her non stop annoyence it's shown in episodes like "Space Cases" that he does care deeply for her,

Dee Dee (Voiced by Allison Moore, seasons 1 and 3; and Kat Creesida, seasons  2 and 4) Dexter's dimwitted, annoying, loud, but loving older sister, who's favorite thing is to mess up and destroy her brother's secret  lab, which she always is able to find a way in, even when Dexter himself can't. While most younger siblings are the ones that annoy the older, here, it's the other way around.

Dee Dee loves her brother very much, which leads to her constantly  pestering him and annoying  him as much as she can. While Dee Dee is often shown to be a loving sister to Dexter, sometimes, she acts like a typical  older sister and gets annoyed with him or picks on him. She is also in some cases shown to be more intelligent then her brother, in terms of life experience.

Dee Dee's favorite hobbies, aside from wreaking Dexter's lab, include your average girly things, such as playing with Pretty Puff Ponies and darbie dolls, (parody of "My Little Pony" and "Barbie"), also enjoys ballet dancing and spending time with her two best friends, Mimi and Lili, who have very much in common with her,