10 (Season 1), 11 (Season 2), 12 (Season 3), 13 (Season 4), 14 (Season 5), 15 (Season 6), 16 (Season 7), 17 (Season 8), 18 (Season 9), 19 (Season 10), 20 (Season 11)





Hair Color


Eye Color

Midnight Blue


Oceanbird (Mother), Windbear (Father), Lalavava (Sister)

Love Interests



Science, destroying Dexter, chaos, being evil


Dexter, Brick, PPG, RRB, being second best

Susan "Mandark" Astronomonov 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 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 Olga. He 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.


He was born Susan Astronomonov in the peaceful land of Flowertopia where his two hippie parents , Oceanbird and Windbear decided to have a baby. The two of them were not married but decided to have him anyway without doing so first. He was born in a lake of water and became their first born lovechild of the Astronomonov family tree. 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 that, he started to cry. He 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. He 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. One day, on his 11th birthday, he had finally had it to the brim with all of his parent's hippie rituals and he threw a fit. He was done with the flowers, the rituals, and the tofu and rice cakes, he wanted science. Oceanbird and Windbear came to the conclusion that they were neglecting their son's needs and so they decided to drop out hoping that they would quench his thirst for evil and impurity. They traveled across the globe showing him the many wonders of the world, and Susan tried going along with it. They went far and wide to help him but even though they did all of that, he still craved to do evil in the acts of science. Eventually, the trio moved into a suburban neighborhood in a nice little home where they would settle with as their new home. He went out for a walk one day there when he came across Dexter who was building an invention of his. When he 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. He 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. He was so annoyed by his laughter and mockery, he became enraged and decided he would no 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
Dex mandark 174x252
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. He was immediately being a smarter student than Dexter and he had officially taken the throne of being the smartest student in the school. He 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. He 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. The next day at school, he was basking in his worship of being the most beloved student around for being so smart, and then came along Dee-Dee, when Mandark first layed eyes upon her he fell madly in love with her. He wanted to get together with her but he didn't know how. Once he found out that Dexter was her brother. He resulted to him for help. Dexter had a plan to become a genius again by setting Mandark up with Dee-Dee. He told Mandark to have her come into his laboratory with him so they could dance together. He did that and when Dee-Dee started dancing, she started recklessly flailing about his lab smashing and destroying everything in it. His laboratory was officially destroyed and Dexter's Laboratory had been put back in business again. His 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, he 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 he 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 him. 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 he was 13, but in the episode A Boy Named Sue, he 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 him 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 createdy by Gennedy Taratovsy, the original creator of Dexter's Laboratory. After season 2 (Excluding Ego Trip and Rude Removal) ended, he 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 him 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 his with Dexter and Dee-Dee's with Lalavava. Since then, everybody in his and Dexter's family have gotten into a rivalry with each other except for their moms. However, in the end of the episode, he 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 he keeps his laboratory a secret from his parents the same way Dexter does. His 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 he was typing in the password to enter his laboratory, he first checked to make sure that nobody was there.


He is an evil boy who is bent on the destruction of Dexter's Laboratory. He wants to be a much smarter genius that him but every time he tries to he always ends up horribly failing. His 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. Although he is evil most of the times, he has a soft side of Dee-Dee.


Dexter: Dexter is his 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. He also is his rival for Blossom's affections, much to her annoyance.

Dee-Dee: He was madly in love with Dee-Dee. She hates him back because he is always trying to destroy her brother but he still can't let her go and is always annoying her.

Olga: Olga is his little sister. She is much younger and smaller then him, but she takes total control over him because she is stronger and more powerful than him. She always scares and abuses him to make him do to whatever she wants.

Oceanbird: Oceanbird is his mother. She does not understand his craving for evil and she wants him to always be nice the same way she is.

Windbear: Windbear is always trying to quench his craving for fighting and evil.

Quackor: Quackor is his 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 had Dexter.



Dr. X sent out Bell to fight Blossom so that he could capture her to become the bait that would lure Dexter to his lab in order to kill him. After Dexter found out what happened he went to his lab and broke in. He was waiting there for him. Dexter saw that Mandark had locked Blossom in a water capsule, that almost would drown her. He and Dexter battled each other with their gauntlets, but Dexter managed to beat him. After the fight Dexter blamed him of the death of Dee-Dee and that he didn't know to have a sister. He told Dexter about his sister Olga. He explained that she was just like Dee-Dee and himself. He almost forgot about her and wondered what had become of her after he left her behind with his parents. He suddenly became mad and thought Dexter wanted to kill Olga and summoned a giant Cluster to fight Dexter. The Cluster grabbed Dexter who became unconscious. Buttercup and Bubbles then came in and destroyed the Cluster and freed Dexter. He saw no other option except to blow up his laboratory and kill Dexter along with himself. He activated several bombs that began to count down. Suddenly the Megas came in to save them and Dexter and the girls. Bubbles said they also needed to save him but Buttercup said there was no time. The bombs were about to explode and he began to cry. The Grim Reaper later appeared seconds before the explosion to take him with him, the lab exploded and killed him. His Glasses glasses were found in the ruins of his lab by his little sister Olga who keeps it with her till this day.


His appearance is a lot different than his appearance from the series. Instead of his school clothes he wears a battle outfit. The outfit is black with some purple thins attatched to it. He made giant robot hands for combat. He has black hair with two cuts at the end that make up the letter M and wears glasses. Though he did appear in his normal clothing from Dexter's Laboratory which is a white blouse with a brown striped tie, blue shorts and brown shoes with long black socks.


He fights in a similar way as Dexter by using his machines for his battles. When he fights hand-on-hand combat, just like Dexter, fights with giant gauntlets, also on his feet. He is shown to summon a metal rope, katana, spike cudgel, wolverine claws, axe, feather, pencil 2, corkscrew, fork, pocket knife and sink out of it. He also was boxing, fencing and light-saber fighting against Dexter.