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Dex mandark 174x252
Character Information
Aliases Susan, Monarch of Darkness, Lovechild, Susie, Sue
Gender Male
Species Human
Family Oceanbird (Mother)
Windbear (Father)
Lalavava (Sister)
Occupation Student, Evil Genius
Production Information
First Appearance "Dexter's Rival"
Voiced by Eddie Deezen

Susan "Mandark" Astronomanov is the main antagonist in Dexter's Laboratory. He hates Dexter because of him being so much of a smarter and better genius than him and he wants to destroy Dexter so that he will be the best genius around. He is voiced by Eddie Deezen.


A bolt of lightning came out of the sky with no exclamation and hit him in the head. This lightning made him become truly evil, but Oceanbird and Windbear were unaware of it while they wanted him to be a good loving lovechild to the earth just like themselves.

His parents wanted to think of a name for him, and so they began describing what kind of name he would get. They wanted a name that was beyond the conforms of society, beyond the preconceived gender connotations, a name that is whispered softly through the canyon winds, and so they named him Susan and the moment they named him Susan, he started crying. Susan hated his life and he hated everything that was happening to him because it was all nothing like what he wanted. 

One day when he was wallowing about his shameful habitat of life, he came across a strangely placed piece of technology that was randomly located right there out in the middle of Flowertopia with know exclamation as to why. Susan loved everything about this thing, he loved the way it looked, the way it felt, the way it worked. He turned it on and it created a bright light of science. If he could only master this thing called science he knew he could control the world. Oceanbird and Windbear however did not approve of this. They believed in living on earth the way it was created, back when it was pure and not overrun by technology, and so they took it from and him and instead did many activities together with him and he hated all of them because they all had nothing to do with technology or science.

Eventually, the trio moved into a suburban neighborhood in a nice little home where they would settle with as their new home. Susan went out for a walk one day there when he came across Dexter who was building an invention of his. When Susan saw this he was fascinated by how outstanding it was. He knew this was science and he wanted to know all about it. He greeted Dexter and wanted to be friends with him. Dexter said he was far too busy and said goodbye to him also calling him a little girl. Susan tried to tell him that he was actually a boy, but because he looked so much like a girl with his long hair and pink dress, Dexter was confused as to how he could be a boy. He asked what his name was and he told him it was Susan. Dexter burst out into laughter over this hilarious incident. Susan was so annoyed by his laughter and mockery, he became enraged and decided he would all longer be nice.

He ran up into his room, and took his light bulb piece of technology and started to build himself an evil laboratory where he would do evil experiments with technology. One that would help him take over the world. He also changed his physical appearance to become more fitting of his gender. He gave himself a bowl-cut hairdo where he literally took a bowl and cut his hair along the rim of it, and he dressed in glasses, a suit, and a tie. Then, he changed his name to a name that would express the darkness that flowed through him, and the man that he knew he would be. He would change his name to Mandark. Then, he found his goal in life, to dominate Dexter, the world, and become the smartest genius ever.

In the episode "Dexter's Rival" Mandark then began going to Huber Elementary School. He happened to have started coming on the first day of school. He sat right next to Dexter in class. Dexter didn't even recognize who he was because he looked so different. Mandark was immediately being a smarter student than Dexter and he had officially taken the throne of being the smartest student in the school. Mandark asked Dexter to show him his secret laboratory. Dexter showed it to him thinking that this would be the one thing that he doesn't have. Mandark looked at it but he was unimpressed by it's lack of creativity. Then, he showed Dexter his own secret laboratory which was so much more highly sophisticated and developed than his. He told Dexter to shut down his laboratory because it was using up valuable power that he could be using to take over the world. He threatened to tell the world about his secret laboratory if he didn't so Dexter shut his lab down.

Mandark's Laboratory being destroyed only carried on into the next episode which was called "Mandarker". In all of the future episodes, his lab had been rebuilt. In some episodes, Mandark was revealed to be the inferior to Dexter being an eternally one-step-behind rival, but in other episodes, he and Dexter tend to be very equally matched.

In the episode "Dee Dee's Rival", it is revealed that he has a little sister named Olga Astronomonov, who goes by the name of "Lalavava" instead similar to how Susan goes by the name of Mandark rather than his real name. She seems to have total control over him because she is stronger and scarier than him. Lalavava got into a rivalry with Dee Dee the same way Dexter did with Mandark. She and Dee Dee treat each other the same way Dexter and Mandark do, only they fight over who is a better dancer instead of who is a smarter genius. Strangely enough, after the episode ended, Lalavava had never been seen or mentioned again.

There were also many seasons 3 and 4 episodes that denied Lalavava even existing to begin with. Lalavava was 8 years old at the time Mandark was 13, but in the episode "A Boy Named Sue" Mandark was having his 11th birthday and a 6 year old Lalavava was not present. Even when the entire family was moving, Lalavava was still nowhere to be seen. In the episode "Mountain Mandark" Oceanbird, Windbear, and Mandark all went out on a family wilderness retreat and Lalavava was still absent. Then again, the 3rd and 4th seasons of Dexter's Laboratory were not officially canon episodes due to the fact that they were not created by Gennedy Tartakovsky, the original creator of Dexter's Laboratory.

After season 2 (Excluding Ego Trip ended, Mandark seems to have built a new laboratory with a more dark, evil look, topped off with a red glow. His laboratory used to have been a yellow and gray glass, bulby, futuristic laboratory. This may have been out of his anger toward Dexter and his evil expanding. The strange thing is that in the episode "A Boy Named Sue" it showed Mandark first building his laboratory and he built it in the creepy gothic look.

In the episode "My Dad vs Your Dad", Dexter and Mandark's dads both got into a rivalry with each other that was very similar to him and Dexter and Dee Dee and Lalavava. Since then, everybody in Mandark and Dexter's family have gotten into a rivalry with each other except for their moms. However, in the end of the episode, Mandark and Dexter bet that their moms could beat the other mom up. It is implied that their moms got into a rivalry just like their dads did but then again, it was still never seen in the show.

It is unknown if Mandark keeps his laboratory a secret from his parents the same way Dexter does. Mandark's Laboratory is aboveground and it is also so big and tall, that it can clearly be seen as a towering laboratory behind his house. It may be possible that he doesn't because it is next to impossible and highly unlikely for his parents to be oblivious to something so obvious like that, but in the episode "A Mandark Cartoon", when Mandark was typing in the password to enter his laboratory, he first checked to make sure that nobody was there.


Mandark is a tall boy who has a black bowl-cut hairstyle that lays around the top of his head like a helmet. It has a white shiny glare on it and an M shaped opening at the bottom. This hairstyle was passed down to him by his father Windbear which was also passed down to his little sister Lalavava. Mandark has a head that is big at the top and gets skinnier at the bottom near his neck. He has nerdy glasses which look exactly like Dexter's and he wears a white dress shirt, a yellow tie with black stripes, blue shorts, and brown shoes.


Mandark is an evil boy who is bent on the destruction of Dexter's Laboratory. He wants to be a much smarter genius than Dexter but every time he tries to, he always ends up horribly failing. Mandark's Laboratory is red, scary and evil looking. The reason for this is because he built it that way out of his anger towards Dexter. He is obsessed with destroying him and getting his revenge on him for being a smarter kid than him and for destroying his lab multiple times.


  • Dexter - Dexter is Mandark's worst enemy. He hates him because he is so much smarter than him and he is always trying to destroy him so that he can be the smartest genius around.
  • Dee Dee - Dee Dee is Mandark's love interest, and is obsessed by her, and if he looks at her he would say, "Dee Dee..." but it hasn't been shown that Dee Dee pays attention.
  • Lalavava - Also known as Olga, Lalavava is Mandark's sister. She is way younger and smaller than him, but she takes total control over him because she is stronger and more powerful than him, similar to Gaz on Invader Zim. She always scares and abuses him to make him do whatever she wants.
  • Oceanbird - Oceanbird is Mandark's mom. She does not understand his craving for evil and she wants him to always be nice the same way she is.
  • Windbear - Mandark's father, Windbear is always trying to quench Mandark's craving for fighting and evil.
  • Quackor - Quackor is Mandark's pet lab duck. Quackor has a supervillain secret identity that he is unaware of and she always goes out being evil whenever he is not looking. In the episode "A Quackor Cartoon", Quackor fell in love with Monkey who was Dexter's pet lab monkey. Mandark was in shock to see this and he fainted and so was Dexter.

Episode Appearances


  • "HA HA HA! HA HA HA HA HA!" - Various Episodes
  • "Please don't hurt me, Please don't hurt me, Please don't hurt me." - Various Episodes
  • "The answer is helium." - Dexter's Rival
  • "Please sir, call me Mandark." - Dexter's Rival
  • "Nooooooooooooooooooooooooooooooooo!!!" - Various Episodes
  • "Mr. Luzinski, may I please be seated in the front of you classroom so that I can obtain the full capacity of your educationally intended teachings." - Dexter's Rival
  • "Yes Dexter, I can read your thoughts and I am smarter than you." - Dexter's Rival
  • "Oh Dexter, it feels as if forever has passed since the day you destroyed my lab." - Mandarker
  • "Was that a Bipolar appendage?" - Rushmore Rumble
  • "After countless experiments, all testing proves negative, no enhanced features, no physical mutations, NO NOTHING!, It seems you shall never become anything more than a mere ducky. Oh well, I guess you're special trick will have to do the job." - Quackor the Fowl
  • "It's bedtime Dexter. PERMANANTLY!" - Momdark 
  • "Chew chew chew, chew chew chew chew chew." - A Mandark Cartoon
  • "WHA HA HA, WHA HA HA HA HA!" - A Mandark Cartoon

Cartoon Network: Punch Time Explosion

Mandark serves as an assist in this game. When he comes out, he pulls out guns that shoot heat-seeking missiles at everyone except for the person who gets him out. He synergizes with the Toiletnator.


  • Mandark's voice actor is Eddie Deezen in the series, but in Cartoon Network: Punch Time Explosion, it is Keith Ferguson, who did the voice of Danny Phantom in Nicktoons MLB.
  • The surname Astronomonov would imply that he is Russian. According to the Animator's Bible he is also half Japanese, because his mother was based on Yoko Ono and he resembles a stereotypical Asian boy. Also, his skin is slightly darker than Dexter's, having a browner, more Asian look.
  • Mandark has a noticeable, strange laugh which appears to always have the same pattern of 3-5. "HA HA HA! HA HA HA HA HA!"
  • In earlier episodes, Mandark's laboratory has a high-tech and more advanced appearance. In later episodes, his lab starts to have a more gothic and crude look.
  • In the first two seasons, Mandark did not wear a tie and his head was shaped like a light bulb. In the next two seasons, he did wear a tie and his head was more triangle shaped.
  • In the Swedish dub, all characters names have been localized or spoken with a Swedish pronunciation with the exception from Mandark. The only character who does not say his name with an English pronunciation is Dexter, which makes him sound very nonchalant.
  • In the episode "Dexter's Rival" Mandark had the ability to read minds; this randomly and suddenly disappeared throughout the rest of the series and even the episode.
  • In Punch Time Explosion XL, he synergizes with Toiletnator.
  • It is implied that Mandark's Parents are not married because in the episodes "A Boy Named Sue" and "My Dad vs Your Dad", Mandark was referred to as a lovechild.
  • Mandark is the same age as Dee Dee who is in the grade above Dexter and is not in any of his classes. However, he is still seen sitting next to Dexter in his class in "Dexter's Rival".
  • In Japanese, Mandark's voice actor is Katsumi Suzuki, who also voices the Red Guy from Cow and Chicken, a fellow Cartoon Network cartoon.
    • Mandark seems to speak rather politely and softly in Japanese; this could be to either make him sound more sophisticated, or to make him sound more traditionally Japanese.
  • Mandark shares some similarities with Princess Morbucks from The Powerpuff Girls: most notably, their rivalries with their respective protagonists are due to jealousy and they have been compared to royalty, Mandark being referred to as a "Monarch of Darkness" and Princess being named after a royal status.
  • Eddie Deezen has stated that Mandark looks like a caricature of himself, and may be based on Malvin from WarGames.
  • In the online web series Yu-Gi-Oh!: The Abridged Series, Mandark ha been referenced multiple times:
    • In one episode, when discussing with one of his Steves on the phone, Marik laughs in a similar fashion to Mandark.
    • One of the clips at the end of an episode features a clip of Seto Kaiba laughing, with Mandark's laugh dubbed in.
    • In the Bonds Beyond Time Abridged movie, Paradox's entire character is rewritten so that he's essentially Mandark (albeit with a speech impediment). He not only sounds like Mandark and has his laugh, he applies the rhythm of Mandark's laugh to the repetition of words ("Yes! It's time to DUEL-DU-DUEL! DU-DU-DUEL-DU-DUEL!"), and this revision was done due to the parallels between Pardox's ultimate goal and the plot of the Ego Trip movie (which both involve saving the future).



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