Vital statistics
Alias Douchebag(Jasper)
Age 15-18
Species Human
Location Tech Square
Nano Item Raygun
Voiced by Eddie Deezen, Scott Menville

Susan Astronominov (born September 9, 1983), commonly known as Mandark, is the main antagonist in the Cartoon Network animated series Dexter's Laboratory. He is the son of Windbear and Oceanbird, and the older brother of Lalavava. Dexter's arch-nemesis. Approximately equal in intelligence to Dexter, he too possesses his own laboratory, which has a red-and-black color scheme (although it was a normal-shaped, brightly lit building before it was rebuilt) and may be organic-based. It is spherical, as opposed to the design of Dexter's Laboratory.

Mandark Industries

Five years after the events of Dexter's Laboratory, Mandark was one of the world’s foremost industrialists and head of numerous design and manufacturing firms. Mandark established his primary base of operations in Tech Square as he and Dexter continue their rivalry. Mandark was also secretly funding the activities of many super-criminals, providing them with advanced weaponry from his factories, and often deploying them against his business rivals. In exchange for his services, Mandark would customarily claim 50% of what his clients had stolen.

Matter of Business

DexLabs would often outshine Mandark Industries in various categories. Mandark, in turn, would steal many of Dexter's ideas and make them "better." Out of all the characters from Dexter's Laboratory, Mandark is the one most mocked, inasmuch as he's still hasn't matured -- he even still wears short pants and suspenders.

When Foster's Home for Imaginary Friends prepared to offer a lucrative business contract to DexLabs, Mandark's employee Carl created a device which could override the cybernetic controls of Dexter's robot assistant, Computress. When Computress went to the Suburbs to represent DexLabs in a meeting with Mr. Herriman and Madame Foster, Mandark used his control over Computress to force her to blast Madame Foster, injuring her greatly. The scandal that erupted resulted in Dexlabs losing its bid with Foster's Home, enabling Mandark to step in and claim the contract. However, Ben and Numbuh Five eventually found and captured Carl, subsequently forcing him to testify against Mandark, thus clearing Dexlabs’s good name.


Mandark confronts an infiltration team consisting of Numbuh 5, Mac, Bloo, and Dee Dee. The group demands his Phase-Pulse-O-Tron needed to complete the Electro-Pulse Cannon. Though initially defiant, his infatuation with Dee Dee led him easily and willingly to hand it over, on the condition that he might assist in the Cannon's activation. Together with a reluctant Dexter, he helped program the EPC to disable the biggest of the first three Terrafusers that landed on Earth. However, Mandark's love for Dee Dee distracted him, leading to a fatal error that prevented the cannon from launching at a crucial moment.


  • Mandark is well-known for his characteristic laugh: "Ha haha! Ha haha haha!"  An entire Dexter's Laboratory episode, "Mandark's Day," was dedicated to its peculiar rhythm.
  • Just as Dexter has the secretly superheroic Monkey as a lab test subject, so Mandark has a test subject, Ducky, who is secretly the supervillainous Quackor the Fowl.