|Portrayed by||Mark Vanselow|
|First appearance||I Am Become Death|
|Home||New York, NY|
|Residences||Reed Street, next to Mohinder's lab|
|Significant other||Mrs. Spatney|
Mohinder investigates a scuffle he hears coming from his neighbor's home and is confronted by Mark, who insults Mohinder for not minding his own business. Mohinder's aggressive anger gives way as he grabs Mark and bangs his head into the doorway until Mrs. Spatney pleads for Mohinder to stop.
Later, Mark heads to Mohinder's lab for revenge. After punching Mohinder in the face, Mark is forcefully pulled into the lab by an angry Mohinder.
Maya brings Mohinder a flyer about his missing neighbor, which Mohinder shrugs off. Soon thereafter, Maya discovers Mark encased in a cocoon. Mark is alive, but unable to move at all, aside from blinking his eyes.
Mark, encased in a cocoon in Mohinder's lab, is discovered by Nathan and Tracy. Tracy tries to free him, despite Nathan's warnings. However, Mark immediately wakes up and grabs Tracy's neck. Nathan tries to free her until Mark is stunned by Noah.
Mark is seen after being recovered by The Company from Mohinder's cocoon, being sprayed down by and cleaned off. Noah tells Meredith they are awaiting a visit from The Haitian to help them "wake up wondering where they've been the last week".
- Mark Spatney is named after Mark Spatny, a visual effects producer for Heroes.
- According to a flyer about Mark, he is 6'3" and has brown hair. People with information about him should call 212-555-0199. Whose phone number this is remains unknown.