|Manner of Death:||Euthanized by Virginia Coady|
|Occupation:||Former Soldier (assumed)|
|Affiliation:|| Project Castor (formerly)|
|Significant Other/s:||Gracie Rollins † (wife)|
|Family:|| Virginia Coady (adoptive mother/creator)|
Gracie Rollins † (wife)
Donnie (half-brother/genetic nephew; via Helena)
Arthur (half-brother/genetic nephew; via Henrik and Helena)
Henrik Johanssen † (father-in-law)
Bonnie Johanssen (mother-in-law)
Abel Johanssen † (brother-in-law)
|Portrayed by:||Ari Millen|
|Season/s:||2, 3, 5|
|First appearance:||"Nature Under Constraint and Vexed"|
|Latest appearance:||"One Fettered Slave"|
Along with the other Castor clones, it is mentioned that Mark and his brothers were brought to Dr. Virginia Coady and the military, where they grew up and received training. Mark was sent to the Prolethean farm to recover information that Henrik Johanssen stole from Project Castor. He becomes a loyal follower of the Proleathean way of life, gaining Henrik's trust and affection. As a Proleathean, Mark was charged with restricted information and crucial tasks.
The character of Mark Rollins first appears in Nature Under Constraint and Vexed. He and fellow fellow Prolethean Damon enter a diner where Sarah is seeking refuge. After inquiring about the diner's eggs to the cook/owner, they propose to abduct Sarah in order to bring her to the newly disappeared Kira. When the cook attempts to interfere, Mark shoots him in the head, instantly killing him, but not before the cook shoots Damon in turn. Mark then chases Sarah through the diner until she escapes into the night.
In Governed by Sound Reason and True Religion, Mark is seen helping Henrik Johanssen (leader of the New Order of the Proleatheans) inseminate a cow while they talk about Helena and their beliefs in God and science. Later, retrieves Helena from the hospital and brings her to Henrik's ranch/the Proleathean home base.
Mark is seen again at the end of Transitory Sacrifices of Crisis. During the night, Mark hides away in a washroom while Gracie sleeps in the next room. He physically burns his skin in an attempt to rid himself of the Castor tattoo on his arm, suggesting that he still no longer wants to associate with his brothers or the military. In Formalized, Complex, and Costly, he is the first CASTOR clone to be made aware of the fact that the CASTOR clones are the genetic brothers to the LEDA clones by Sarah Manning.
|Season 2 appearances|
|Nature Under Constraint and Vexed||Governed by Sound Reason and True Religion||Mingling Its Own Nature With It||Governed As It Were By Chance||Ipsa Scientia Potestas Est|
|To Hound Nature in Her Wanderings||Knowledge of Causes, and Secret Motion of Things||Variable and Full of Perturbation||Things Which Have Never Yet Been Done||By Means Which Have Never Yet Been Tried|
|Season 3 appearances|
|The Weight of This Combination||Transitory Sacrifices of Crisis||Formalized, Complex, and Costly||Newer Elements of Our Defense||Scarred by Many Past Frustrations|
|Certain Agony of the Battlefield||Community of Dreadful Fear and Hate||Ruthless in Purpose, and Insidious in Method||Insolvent Phantom of Tomorrow||History Yet to Be Written|
|Season 5 appearances|
|The Few Who Dare||Clutch of Greed||Beneath Her Heart||Let the Children and Childbearers Toil||Ease For Idle Millionaires|
|Manacled Slim Wrists||Gag or Throttle||Guillotines Decide||One Fettered Slave||To Right the Wrongs of Many|
- Mark's haircut was based on those of World War I and II soldiers to ensure he stood out as an outsider.
- Sarah noted that Mark was different from his brothers
- Supporting this is Mark wanted out of the military, so he could live his final days with his wife.
- ↑ The Hive Recap: Governed by Sound Reason and True Religion. BBC America (April 27, 2014). Retrieved May 12, 2014.