Olga Astronomonov is the second child of Oceanbird and Windbear and the younger sister of Mandark. Like her brother, she cast aside her given name and took on a name of her own choosing: Lalavava.
Young Lalavava is not like other little girls. She does not enjoy happy, childish things and is instead drawn to frightening and depressing matters. She enjoys being rude and scary to others and goes out of her way to make everyone else as miserable as possible. Despite her being only an eight years old child, everyone is pretty much terrified of her.
Lalavava is especially rough on her brother, Mandark, whom she bullies mercilessly. Despite his genius intellect, Mandark does whatever his sister wishes allowing her to treat him like her slave.
Oddly, Lalavava took a keen interest in ballet and proved to be quite good at it, very much impressing the other students at the dance school. This proved quite threatening to Dee Dee, who prided herself on being he best dancer at the school. Hence, just as Mandark is arch enemies with Dexter, Lalavava became the arch enemy of Dexter’s sister, Dee Dee.
Actor Eddie Deezen provided the voice for Lalavava with the tiny tyrant first appearing in the 35th episode of the second season of Dexter's Laboratory, airing on April 15th, 1998.
I am so very glad you could come. There are so many things I want to show you, all kinds of marvelous science and invention and tools and technologies, all of which you sparked with your little flame, so I bid you welcome. Welcome to Dexter's laboratory!
Dexter's Laboratory
Season 2, Episode 28a “Old Flame”
Air date: February 25, 1998