Mason Hewitt is a sophomore at Beacon Hills High School and an ally of Scott's Pack. He was the eleventh and final test subject in the Dread Doctors' current experiment pool in Beacon Hills. Mason was the success of the Doctors' experiment and their centuries' long work, becoming the vessel for the Beast of Gévaudan. Mason had genetic chimerism due to his being born with vanishing twin syndrome. Naturally and inherently good-hearted, kind and compassionate, Mason was an ideal candidate for being one who was 'truly good' for the Doctors whom they had to find a way to corrupt. The process worked and Mason became the Beast's vessel, causing him to periodically transform into the Beast's demonic werewolf shape.

 

The Dread Doctors, having perfected the Chimera process, now want the Beast to remember itself as its original deceased human incarnation and identity, Sebasten Valet. The Dread Doctors use powerful sonic frequencies to trigger Mason's transformation into the Beast and arrange for the beastly werewolf to gradually remember more of its former life to also gradually bring back Sebastien from the dead. The Doctors succeed in their actions, the Beast remembering its real name and Sebastien is revived, leaving Mason Hewitt erased from existence, but lives on as memories. Mason is saved by Scott's Pack who have the Beast remember itself as Mason Hewitt and Mason is freed, separated from the Beast's spirit.

 

Theodore "Theo" Raeken is the very first Chimera produced from the Dread Doctors' experiments. Nine years prior to the series, Theo was chosen to be a Chimera by the Doctors. They saw him as a perfect candidate for being the 'perfect evil' as Theo was a sociopath: he would willingly murder his responsibly caring sister as a child. After Theo killed his sister, he sister, he became a genetic chimera after the Dread Doctors harvested his sister's heart and transplanted the organ into him. The para-scientists eventually failed with Theo, but his failure was a turning point in their research, so they allowed him to survive. Afterwards, Theo became partners with the Doctors. He served the Dread Doctors during Season 5 by being their spy amongst Scott's Pack as they conducted their most recent line of experimentation, to find then experiment with truly good test subjects being corrupted. After the Doctors killed off the failures, Theo forms a pack with four of the failures, bringing them back to life, Hayden Romero, Corey Bryant, Tracy Stewart and Josh Diaz.

 

Theo is a Chimera hybrid of both a werewolf and a werecoyote. He shows the physiological traits and powers of both shapeshifters, including pack symbiosis, a 'Beta' werewolf transformation, strength, reflexes, endurance speed and senses. His werecoyote part allows him to shapeshift into both a full wolf and a full coyote form. Though Theo is a killer, he permanently displays the gold eyes of an innocent and cannot rise to alpha rank in the supernatural sense. Theo then kills Josh and Tracy, to the steal their sparks of power, gaining the capabilities of a kanima and electrokinesis, producing kanima venom and his abilities and healing factor all being heightened.

 

Hayden Romero is a sophomore, and soccer player at Beacon Hills High School. She is genetically a chimera from a kidney transplant she had a few years previously. After being incubated by the Dread Doctors, she becomes a Chimera. Hayden is brought into the supernatural world through Scott's Pack and becomes the girlfriend of Liam Dunbar. Hayden is declared a failure and is killed by the Dread Doctors. Later, she is revived by Theo Raeken using the Soldier's blood to be part of his pack of Chimeras. Hayden rediscovers her humanity and leaves Theo for Scott's Pack so she can be with Liam. Hayden then completely loses her Chimera nature after willingly being bitten by Scott McCall, becoming a true supernatural beta werewolf.

 

As a Chimera, Hayden was a werewolf and werejaguar hybrid. She has the natural abilities and traits of both species. She has heightened enhanced speed and senses. Her werewolf half gives her the talent to take pain from others and pack symbiosis. Her werejaguar part is known to allow her to sense and track berserkers including the berserker Chimera Noah Patrick.

 

Tracy Stewart is a senior at Beacon Hills High School. She has chimerism due to her having an allogeniac skin graft. Tracy was the first Chimera in the Dread Doctors' newest experiment pool. When she became a Chimera, Tracy's transformations manifested to her as night terrors due her disorder. Eventually Tracy became psychologically locked away in her disorder from her being under the Dread Doctors' mind control, resulting in her having homicidal somnambulism. She went goes on a killing spree, including killing her own father, until she pukes up mercury, indicating she is a failure and she is killed. Tracy is then revived by Theo Raeken using the Soldier's blood to form his Chimera pack, and Tracy becomes his most loyal, and most ruthless combatant and right hand. Tracy is then killed by Theo to steal her power.

 

As a Chimera, Tracy is part werewolf and part kanima. In her transformation, she manifests the claws and fangs of a werewolf, has a wolf's instinct to follow her alpha and the symbiosis from being in a pack of canine werecreatures, but mainfests the hide, venom and the wall-crawling abilities of a kanima. Tracy has heightened strength, speed, agility and reflexes and an extremely heightened healing factor. Her abilities were the most potent in Theo's Chimera Pack. Her spark of power is stolen by Theo.

 

Josh Diaz is a junior at Beacon Hills High School. Josh was the fourth Chimera in the Dread Doctors' Beacon Hills' line of experiments. He is a carefree party-goer who drank and took drugs recreationally. The Dread Doctors' plan for Josh's corruption was to have him become feral. Josh became animalistically hungry for electricty, gnawwing on electric cables at the high school and Beacon Hills Hospital. When Josh is declared failure, he is killed by Theo Raeken at the Doctors' behest. Josh is then revived by Theo later with the Soldier's blood to be part of his pack to serve him as his alpha. Like Hayden and Corey, Josh rediscovers his humanity. Theo then kills Josh again to take Josh's electrical power.

 

Josh is part werewolf, like many of the other Chimeras, and part electric eel. He has the natural wolf instinct to run with a pack. His transformation consists of werewolf claws with overlarge front teeth. Josh has the power of electrokinesis from his electric eel makeup he can detect, absorb and weaponize electricity.