|Full name:||Cosima Niehaus|
|Birthdate:||March 9, 1984|
|Residence:||Minneapolis, Minnesota, USA|
|Portrayed By:||Tatiana Maslany|
|Latest Appearance:||"Endless Forms Most Beautiful"|
- "Right. I'm 324b21."
- —Cosima discovering her "tag number"[src]
Cosima Niehaus is a clone of American origin on Orphan Black. She befriended Sarah Manning whilst she was under the guise of Beth Childs shortly after the death of fellow clone, Katja Obinger. Since then, Cosima has aided Sarah in her pursuit of their true origin, alongside Alison Hendrix. After discovering that the individual whom she had become intimate with was also acting as her monitor, Cosima fled to Canada from the United States to join Sarah and Alison. Unfortunately, during this time, Cosima developed a respiratory illness which Katja had also been a victim of. Cosima was eventually able to uncover the fact that they are property of their creators.
Much of Cosima's past is still unknown, except that she is from San Francisco, California, studied at UC Berkeley, and is currently completing her PhD in Experimental Evolutionary Developmental Biology at the University of Minnesota.
Beth Childs managed to find her and another clone, Alison Hendrix, through a facial recognition program after Katja Obinger contacted Beth about three other clones in Europe. They have been looking after each other ever since. Meanwhile, the sick Katja, who wanted to see Cosima, whom she knew as a scientist, was asked to submit proof of the European clones' predicament to Beth. Prior to Beth's suicide, it seemed that Cosima constantly called her for updates.
After Sarah Manning assumed Beth's identity, Cosima still kept constantly calling Beth's phone. Sarah only picked up after Katja was killed in front of her in "Natural Selection". When Sarah informed her that the German was dead, they both panicked momentarily; finally realizing that Katja was telling the truth about someone wanting them dead. Cosima then advised Sarah to get rid of the body and find Katja's suitcase with the proof they need in a hotel that she stayed in.
For a while, she believed that she was actually in contact with Beth. That is, until Sarah retrieved Katja's briefcase and frustratingly came clean in Instinct. Cosima, in a moment of confusion, hung up. Sarah tracks down Alison, thinking she was the caller, but is later introduced to Cosima at Alison's house. Cosima tried to explain their predicament calmly to Sarah and later stressed the importance of the briefcase to them in Variation Under Nature. Sarah eventually met up with Cosima at a local bar on the day she is set to return to Minneapolis for her studies. They also finally discussed the fact that they are clones, with Cosima finally convincing Sarah to give her the briefcase so she can study and analyze the samples inside.
She, Sarah and Alison often video chat, and Sarah often calls Cosima for help and keeps her in the loop of things. Cosima is the science-side of the clones, using her knowledge and resources to dig further into their creation and genetic makeup.
Upon her return to Minneapolis, Cosima immediately begins working on comparing the blood samples of her fellow clones, particularly to find out if they might have the same disease Katja had. She soon meets the charming French student, Delphine. Cosima is almost immediately suspicious of her, telling her fellow clones that she thinks new friend might be her monitor. Despite her suspicions, Cosima befriends Delphine, pretending to be monitoring her instead.
Cosima, however, finds herself very taken by her and, wanting to trust Delphine, makes a pass at her. Initially unsure of how to approach her, with Aldous Leekie's urging, Delphine begins a relationship with Cosima and unwittingly falls for her, as well. Delphine continues to report her discoveries in her room to Leekie when she finds out that Cosima's life may be in danger.
When Sarah tells her that someone sold them out to Leekie, Cosima soon discovers Delphine's true identity and that she had in fact been spying on her for Leekie and confronts her about it. Initially avoiding her after their fallout, Cosima finally faces Delphine when she follows her all the way to Canada and the pair make amends. Cosima continues to investigate their genetic makeup and, with the help of Delphine, uncovers the portion in their genome which contain their tag numbers and their creators' patents on them.
Cosima is an eccentric, queer, tattooed geek girl with a scientific mind verging on genius. She's dependable, incredibly caring, brave, driven to find answers and, like Sarah, adaptable to extreme circumstances. She also tends to diverge on scientific topics and can talk relatively fast when she gets excited.
Cosima usually wears her hair in intricate dreadlocks. In addition to her tattoo, Cosima also has a nose ring. According to Felix, Cosima has bigger breasts than Sarah and is apparently more attractive.
- Cosima was named after Orphan Black's own "Science Consultant", Cosima Herter.
- Her tag number, the number that identifies her among the clones, is 324B21.
- In Effects of External Conditions, she is shown to be smoking marijuana. She later admits to Delphine that she only smokes this and never cigarettes in Variations Under Domestication.
- She is shown to have a taste for wine as she was seen having a glass in a bar in Variation Under Nature and stealing two bottles from Leekie's reception in Variations Under Domestication.
- Her laptop is covered with a laptop skin designed with multi-colored DNA strands and carbon rings.
- In an interview, Tatiana states that the writers mentioned to her that Cosima was bisexual, though Tatiana feels that Cosima simply just loves people.
- The reason that Cosima wears glasses and her clones do not is due to the fact that her sight degenerated due to her enviroment and conditions. She just studies too much.
- The actress, Tatiana Maslany, who plays the clones, uses music to differentiate the clones. Her playlist for Cosima is electronica, including artists such as Diplo and Grimes . Maslany has described it as "beeps and boops kind of stuff." 
- ↑ http://www.bbcamerica.com/orphan-black/2013/03/30/qa-with-cosima-herter-science-consultant/
- ↑ http://www.afterellen.com/2013/05/tatiana-maslany-gives-us-scoop-orphan-black-clones-and-cosimas-bisexuality
- ↑ http://media.tumblr.com/09092d654307bbd297add54e74bf66ad/tumblr_inline_mo5qxeGW7E1r1zt3k.png
- ↑ http://youtu.be/iQZGNST8MCQ?t=16m25s/