|First Appearance||Babysitter Blues|
|Voiced By||Kath Soucie|
She is a tall female adolescent with strawberry blonde hair, fair skin, blue eyes and has a slender but curvy figure. She wears a white top with a blue plaid skirt, white kneesocks, black shoes, a light blue hair band and a black belt with a yellow buckle around her waist.
Lisa is shown to be very kind and friendly, and is evidently very good with children, seeing as she's a part-time babysitter. She is completely oblivious to Dexter's crush on her, though. She is affectionate to Dexter, giving him a kiss when he opens the door for her.
Mom and Dad are going on a date, so they leave Dee Dee and Dexter with their babysitter, Lisa, who has apparently babysat for Mom and Dad before. Dexter has a crush on Lisa and wants to get her to like him, but his plans fall through when he finds out that Lisa has a jock-boyfriend named Jeff.
Dexter comes up with a plan to break up Jeff and Lisa. He goes to his laboratory and disconnects the phone line at his, which temporarily ends the conversation between Lisa and her boyfriend. First, Dexter calls Jeff and digitally disguises his voice to sound identical to Lisa, and "breaks up" with Jeff.
Then Dexter calls Lisa and digitally disguises his voice to sound identical to Jeff, and "breaks up" with Lisa, greatly upsetting her. When Dexter goes to comfort Lisa, and tells Lisa that she should go for the more bookish type instead. Lisa finds this sweet and tells Dexter that she'd definitely date him if he was ten years older---which gives Dexter the idea to enhance his age by ten years.
However, Dexter's teen self isn't nearly as handsome as he initially imagined, as he looks like a stereotypical nerd, and his appearance ends up frightening Lisa away.
- It is unknown how old Lisa and her boyfriend, Jeff, are, but they're presumably around sixteen to eighteen years old, due to Lisa's comment on dating Dexter if he were ten years older.
- It is unknown if Jeff and Lisa got back together after Dexter broke them up.
- Lisa's pet name for Jeff is "Fuzzy Lumpkins," which is the name of a recurring villain on The Powerpuff Girls.