There is evidence that the Doctors made several, possibly hundreds, of earlier chimera as detailed in Dr. Valack's The Dread Doctors (Novel) The book details experiments by the Dread Doctors that took place in a small New England town many decades before the events seen in Teen Wolf Season 5.
The process of manufacturing supernatural creatures in the Teen Wolf universe begins with humans who have two distinctly different sets of DNA present in their body. This can be the result of transplanted donor tissue, bone marrow transplant or fetal absorption (vanishing twin syndrome) invitro.
The Dread Doctors used mostly unknown means to graft supernatural abilities onto the two DNA types meaning each of their creatures would have attributes of at least two different supernatural creatures.
From details shown on screen, the process involves collecting samples from real supernatural creatures. The seepage from an unhealed wound inflicted on Garrett Douglas by Ghost Riders during World War II is also used in the process. Douglas was a natural werewolf/lion chimera the doctors imprisoned in a fluid-filled tube in their laboratory. The liquid in the tube is infused with the trans-dimensional energy of the Wild Hunt and is apparently key to the doctors' efforts. The fluid also appears to prolong the doctors' lives.
After introducing the supernatural elements into their young victims, the doctors bury them in holes in the ground. Days later, the subjects emerge with no memory of their experience with the doctors.
|Belasko||Glowing Garuda Claws||Creatures of the Night|
|Belasko seemed to absorb power from Jordan Parrish and from Scott McCall through eagle-like talons that glowed blue. When stabbed by The Surgeon, his chest split open and several crows flew out. Belasko was played by Gabriel Hogan.|
|Theo Raeken||Werecoyote Transformation||Status Asthmaticus|
|While he presented himself as a bitten werewolf, Theo Raeken is one of the Doctors' early experiments. He is able to fully shift and claims this is thanks to the werecoyote part of his makeup.|
|Tracy Stewart||Kanima Venom, Features, Tail||Dreamcatcher|
|With the Doctors intervention, Tracy became a Kanima Hybrid with the claws of a werewolf and the scales and venom of a Kanima. She did not remember her transformations and her mind handled them as dreams leading to night terrors. The Doctors injected her with something and, from that point, she set about killing anyone who had tried to help her. She is killed by the Dread Doctors and returned to life by Theo.|
|Lucas||Scorpion Stingers, Eyes, Venom||Condition Terminal|
|According to his boyfriend, Lucas was usually shy and reserved but suddenly changed and became overconfident and aggressive. Sharp spines full of scorpion venom emerged from his skin. His stings were extremely painful to the point that morphine could not ease the victim. He showed great strength besting Brett, Scott and Kira. Liam eventually brought him down. Lucas was played by Eddie Ramos.|
|Donovan Donati||Wendigo Teeth, Eyes||Condition Terminal|
|The Doctors catch Donovan after his escape from the prison van, drill into his head and let him go. After taking him from the Sheriff's Station, the Doctors remove his teeth with pliers. His mouth fills with blood then new teeth, sharp in two rows, grow back immediately, Wendigo teeth. His transformation was ongoing. Toothy mouths appeared in his hand and neck. He attacks Stiles but is impaled and killed. Parrish takes his body.|
|Josh Diaz||Sharp Teeth, Electricity Absorption||Required Reading|
|A chimera being part eel, Josh is first seen chewing through the wires on the roof of Beacon Hills Memorial Hospital. He later attacks Stiles and is killed by Theo. It is as yet unknown what species went into making Josh a chimera. His teeth were larger than any shapeshifter seen on the show to date. Josh is returned to life by Theo.|
|Hayden Romero||Eyes, Fangs, Jaguar-like spots||Strange Frequencies|
|Liam discovers Hayden is a chimera and seeks to protect her from the Dread Doctors. The Doctors say her condition is worsening. A wound in her side was slow to heal but eventually did completely. She died and was returned to life by Theo. She is apparently part Werejaguar and has the ability to sense Berserkers.|
|A Chimera named Zach has what appears to be the stubs of wings growing out of his back. He explains that part of the process of becoming a Chimera involves a period of memory loss followed by violence. He says once you begin to bleed silver, the Dreads come for you. He begins to bleed silver and the Doctors take him away. He is played by Ben Stillwell.|
|Unknown Female||Long, Needle-Like Claws||Strange Frequencies|
|The body of a girl who appears to be a chimera was found at the McCall house with Kira's sword sticking out of her chest. She had needle-like claws. No other information about her is available.|
|Corey||Ghost Rider invisibility||Strange Frequencies|
|In addition to rapid healing and moderately increased strength, Corey displays the ability of the Ghost Riders to slip between dimensions and become invisible. He can share this ability by touching others and taking them with him and he can make Ghost Riders visible to everyone by touching them and bringing them back with him. Corey is one of the chimera returned to life by Theo.|
|Beth||Unexpressed||Lies of Omission|
|Beth is a student in one of Malia's classes who began exhibiting signs of chimeria failure in class. She was killed at school by The Pathologist. She is played by Lexi Aisworth.|
|Noah Patrick||Long Bone Spikes, Strength||The Last Chimera|
|This chimera is seen eating bags of blood plasma. He has long spikes protruding from his arms and very sharp teeth. He is identified as Noah Patrick a sophomore. He apparently attacked Sheriff Stilinski and left him near to death. Theo says he is part Berserker. Noah dies at the hands of the Dread Doctors. Noah was played by actor Jordan Fisher.|
|Mason Hewitt||Host for Sebastien Valet||The Beast of Beacon Hills|
|He absorbed his twin in the womb which made him have two sets of DNA to make him a genetic chimera. He is the success of the Dread Doctors experiments.|
All but two of the Chimera were considered failures. Theo Raeken and Mason Hewitt were considered successful chimera, Theo because his mix of werewolf and werecoyote proved stable and Mason because he could successfully host The Beast and revive Sebastian Valet.