As seen in the episode, "Dee Dee's Rival".

Oh please, maim. Call me... Lalavava!
~ Lalavava

Olga "Lalavava" Astronomonov, also known as Lala Fafa, is the younger sister of Mandark and a one-time antagonist in Dexter's Laboratory. Mandark's sister is 8 years old and was the second in line of the evil children of the hippy pacifists - albeit she is the little-known one.

Like her brother Mandark, Lalavava was voiced by Eddie Deezen with a slightly high-pitched voice.


However, unlike Dee Dee, she is not an quite so ditzy, and Mandark fears her. This is very similar to how Gaz is depicted on Invader ZIM. He shares some certain similarities with his younger sister, and they are both the opposites and rivals of Dexter and his sister, Dee Dee, the latter of whom he is madly in love with. Lalavava and her brother, Mandark, look very similar, in contrast to Dexter and Dee Dee.

Unlike their brothers, however, Lalavava and Dee Dee end up becoming friends. Dee Dee and Lalavava instead go to the mall while both agreeing that science is lame.