Ira
Unlike his clone brothers, Ira was raised outside of the military faction, Project Castor. Instead, he was adopted by Susan Duncan, one of the original scientists who created the female clones. He continues to work in research to find cures for the illnesses that plague him and his fellow brother and sister clones.
Parsons
Parsons was experimented on brutally by Project Castor. Helena came upon him while escaping from her prison cell and he begged her to put him out of his misery. She obliged.
Seth
Seth was very close to Rudy. He was sick, though, from some kind of neurological disorder that affects many of the male clones. Much of Rudy's desire to find the Castor genome stems from wanting to cure his brother. But before he can do that, Seth suffers from painful seizures and Rudy shoots him dead to end his suffering.
Rudy
Rudy is an especially smart and determined Project Castor clone. His search for the original Castor genome places him in conflict with Sarah. Believing she knows something about the genome's whereabouts, he kidnaps Sarah's daughter as ransom for information. Later, he is killed by Helena while she's on a mission.
Styles Miller
Another Project Castor clone and soldier, Styles Miller was central to the capture and torture of Helena. He was killed by Paul Dierden, the man assigned to monitor Beth Childs and later Sarah.
Mark Rollins
Mark Rollins is part of a male line of clones born from the DNA of Kendall Malone. How's that possible? While in the womb, Kendall had a twin brother whom she absorbed. The female clones are born of her DNA while the male clones are made from her brother's DNA.
Mark is a self-aware clone and was a loyal member of the military cloning faction, Project Castor. He has since showed a desire to leave the organization.
Veera Suominen AKA Mika
Veera Suominen, who's also known as M.K., is from Helsinki, Finland. After living through a tough upbringing, and surviving attempts on her life, she met Beth. She's an expert computer hacker and holds information that would be vital for the clones if they win her trust.
Krystal Goderitch
Krystal Goderitch is another Canadian clone. Although she's seen some strange things and survived a kidnapping, Krystal doesn't know she's a clone. That doesn't mean she can't help the others with information.
Charlotte Bowles
Eight-year-old Charlotte Bowles (Cynthia Galant) is the first clone to be made from Sarah's batch in 20 years. It's discovered that she has an early-onset version of the respiratory illness that plagues her sister clones.
She has been kidnapped by Neoevolution, a scientific organization dedicated to self-directed human evolution.
Tony Sawicki
Tony Sawicki was formerly known as Antoinette Sawicki. Yes, he's a transgender clone. Tony was in contact with Beth, who told him they were related but didn't say how. That job went to Sarah, since Beth was dead.
Jennifer Fitzsimmons
An American clone, Jennifer Fitzsimmons is only seen through a video diary. She suffered from the same respiratory illness as other clones, but accepted Dyad's offer to treat her. She detailed the treatments in her videos, but her health continued to deteriorate.
An autopsy of her body would deliver huge clues as to the illness affecting the clones, including that the illness grew from Jennifer's uterine wall, may have made her infertile, and spread through her body from there.
Rachel Duncan
Raised in England by her adoptive parents, who were also the scientists who created the clones, Rachel Duncan was raised with the knowledge that she's a clone. Working closely with an organization that wants to advance human evolution with cloning, Dyad, Rachel wants other self-aware clones to support Dyad's mission.
That places her in direct opposition to Sarah and the other clones. She's also quite jealous of Sarah's ability to have children and covets her daughter, Kira, sometimes to a dangerous level.
Helena
Helena was brought up in the Ukraine. She was raised by religious zealots who knew of the illegal cloning program. They taught her that she was an original among them and needed to kill all the others. She's the one who killed Katja. Here's the twist: She is Sarah's twin. And like Sarah, Helena is able to get pregnant and does. She's currently carrying twins. Having been captured and tested on by a religious group who believe genetic biology is God's will, Helena forges a closer friendship with Sarah and the other clones.
Cosima Niehaus
Cosima Niehaus is an American clone who was working with Beth and Alison. Believing Sarah was Beth, she's the one who helped Sarah through Katja's murder and led her to the briefcase of information about other clones. After finding out that Beth is actually Sarah, they become friends, along with Alison, and team up to find out more about their clone origins. They dubbed their alliance the "Clone Club."
Like Katja, Cosima suffers from a respiratory illness that causes her to cough up blood.
Alison Hendrix
Alison Hendrix is another Canada-based clone who was working with Beth and Katja. She's married and has kids, so her biggest goal is to keep her family safe and her suburban life intact. Nevertheless, she's a tough cookie who becomes a great source of information and support for Sarah. Later, Sarah returns the favor when Alison begins to act out of paranoia and Sarah helps her snap out of it.
Katja Obinger
German clone Katja Obinger was secretly working with Beth and had discovered other clones. Unaware that Sarah was impersonating Beth, she tried several times to get in contact with Beth but Sarah was unaware of their connection. Apparently sick and with a theory that someone was trying to kill the clones, she was suddenly shot dead after realizing Sarah was impersonating Beth.
Sarah gets a hold of a briefcase owned by Beth and discovers the identities of other clones inside.