<Li> Ari Millen as a number of male clones ( see here ) -- the result of a sister project to Project Leda : Project Castor , a top - secret military program . Unlike their Leda counterparts , the Castor clones have always been aware of what they are , being raised together by the US military ; their caretaker was Virginia Coady , who they refer to as Mother . They suffer a mental defect , which basically turns their brains to , quoting Scotty , `` Swiss cheese '' after set amount of time ; unfortunately the defect is also an STD , which sterilizes women . Coady studies this , often sending Rudy off on leave to infect new test subjects . The first Castor clone to be introduced to the viewers is Mark Rollins , coming off as a homicidal Prolethean , before being exposed as an undercover Castor agent ; he marries fellow Prolethean Gracie Johanssen after running away from the Prolethean farm , wanting a normal life with her before his defect kills him . Other major Castor clones includes the menacing scarefaced Rudy , the tormented Seth , the crippled Miller and the Neolutionist Ira . All the Castor clones are now deceased , with Mark , the last , executed by Coady . ( recurring season 2 ; regular season 3 -- 5 ) </Li>
<Li> Ari Millen as a number of male clones ( see here ) -- the result of a sister project to Project Leda : Project Castor , a top - secret military program . Unlike their Leda counterparts , the Castor clones have always been aware of what they are , being raised together by the US military ; their caretaker was Virginia Coady , who they refer to as Mother . They suffer a mental defect , which basically turns their brains to , quoting Scotty , `` Swiss cheese '' after set amount of time ; unfortunately the defect is also an STD , which sterilizes women . Coady studies this , often sending Rudy off on leave to infect new test subjects . The first Castor clone to be introduced to the viewers is Mark Rollins , coming off as a homicidal Prolethean , before being exposed as an undercover Castor agent ; he marries fellow Prolethean Gracie Johanssen after running away from the Prolethean farm , wanting a normal life with her before his defect kills him . Other major Castor clones includes the menacing scarefaced Rudy , the tormented Seth , the crippled Miller and the Neolutionist Ira . All the Castor clones are now deceased , with Mark , the last , executed by Coady . ( recurring season 2 ; regular season 3 -- 5 ) </Li>
who plays the boy clones in orphan black
who plays the boy clones in orphan black
Ari Millen
Ari Millen