|Olga "Lalavava" Astronomonov|
|Interests||Ballet, Misery, The suffering of others especially Dee Dee, Abusing Mandark|
|First Appearance||Dee Dee's Rival|
|Voiced by||Eddie Deezen|
Lalavava "Olga" Astronomonov is an evil and scary little girl who is Dee Dee's rival, Mandark's little sister and second born Lovechild of Oceanbird and Windbear. She appeared in the episode Dee Dee's Rival where she and Dee Dee both got into a fight over who was a better dancer. She is voiced by Eddie Deezen.
Lalavava made her debut, and only appearance, in the episode "Dee Dee's Rival" as a major antagonist to Dee Dee, much in the same way as Mandark is to Dexter. In fact, she is designed in a way to parallel this role. While Dexter is short and blocky with a tall, lanky sister, Mandark is tall and lanky with a short, blocky sister about the same height as Dexter. However, unlike Dee Dee, she is not quite so ditzy in fact more horrifying and evil and very smart at that. She is also very strong and Mandark fears her.
After competing with Dee Dee as the ultimate ballerina of their ballet school, most notably in their stage performance where both of them used giant robots created by their brothers, Lalavava eventually became friends with her. They called it a truce after a fellow ballerina who was unintentionally tormented by the girls' robots' trips on the stage, garnered the audience's admiration. Dee Dee and Lalavava instead went to the mall while both agreeing that science is lame. After the episode "Dee Dee's Rival", Lalavava was never seen or mentioned again.
Lalavava is a short little girl who has black hair that looks exactly like her brother Mandark's only she has in ponytails in it. She wears a pink dress and white knee socks and pink slippers just like Dee-Dee.
Lalavava is not like other little girls. She is not happy and childish like they are and she does not enjoy doing happy things. She is a dark and scary girl who acts very rude and evil. She takes a liking dark and depressing scary things and making the lives of other people miserable by doing things such as abusing her brother Mandark and treating him like a slave. She seems to be much stronger than him despite the fact that she is an eight year old girl and he is thirteen year old boy. Lalavava seems to go out of her way be rude to everyone in her life and make them miserable and unhappy for no given reason. However, despite all of this, she seemed to have taken a liking to ballet and impressing the other students at the dance school which would seem unlike her behavior but she probably did just because she knew that Dee Dee was happy with being the best dancer at the school and she wanted to ruin that for her.
Dee Dee - Dee Dee is Lalavava's worst enemy. The two of them are always getting into fights and battling each other the same way their brothers Dexter and Mandark do. Dee Dee usually wins because she is good while Lalavava is evil, but just like Dexter and Mandark, they are very evenly matched and sometimes neither of them win and it ends up in a tie. At the end of the episode Dee Dee's Rival the two of them became friends
Mandark - Lalavava has complete and total control over her older brother Mandark. She is able to beat him up easily and can boss him around telling him to do whatever she wants. Whenever she threatens to hurt him he always says this recurring quote, "Please don't hurt me, Please don't hurt me, Please don't hurt me." Mandark is usually so strong and evil, but when Lalavava comes up to him, he is a complete wuss and a slave to her and all of he demands. her voice sounds like mandark
- "Please Maam, call me Lalavava" - Dee Dee's Rival.
- "Mrs. Babcock, I know that you are very busy with multiple other students, so allow me to do you a favor and go first." - Dee Dee's Rival.
- "Use your nerdy sciencey junk to help me destroy that skinny creep." - Dee Dee's Rival
- "Do it, or else I will break your scrawny nerdy face!" - Dee Dee's Rival
- Although she only appears in one episode of Dexter's Lab, she remains a main character in Bleedman's webcomic series, "Power Puff Girls Doujinshi" as a possible love interest to Dexter.
- She was voiced by Eddie Deezen, who also voiced her brother Mandark.
- While Mandark met Dee Dee and fell in love with her in "Dexter's Rival", Lalavava doesn't fall in love with or even meet Dexter in "Dee Dee's Rival".
- She was absent in the episode "Mountain Mandark" where Mandark, Oceanbird, and Windbear all went out on a family nature hike.
- She's the only member of the Astronomonov family who doesn't wear glasses.
- The reason she was not seen in any future episodes where Mandark's family was seen, but all that was seen was Oceanbird, Windbear, and Mandark, is probably just a plot hole or a continuity error.
- It is possible that Oceanbird and Windbear address her by the name of Olga the same way they address Mandark as Susan.
- Lalavava is basically the opposite of Dee Dee.
- Lalavava is evil while Dee Dee is good.
- Lalavava is short while Dee Dee is tall.
- Lalavava likes dark, evil, miserable things while Dee Dee likes frilly, girly, happy things.
- Lalavava is smart while Dee Dee is stupid.
- Lalavava's hair is dark black while Dee Dee's hair is bright yellow.
- Lalavava abuses and hates her brother while Dee Dee respects and loves her brother.
- Lalavava is scary while Dee Dee is cute.
- Lalavava is always angry while Dee Dee is always happy.