The Chimera is an ancient weapon of mass destruction.
"A thing of immortal make, not human, lion-fronted and snake behind, a goat in the middle, and snorting out the breath of the terrible flame of bright fire." - The Iliad
Many thousands of years ago, the priests of Lanthis got into a complicated relationship with Mayahuel, who taught them to make golems. Two young women (Brandilyn Oduya and Acacia Budur) were abducted, taken to a temple, and tortured; a third (Tochtli) was found tampering with the process and was thrown in herself. All three were killed, cremated, and their ashes mixed together with clay to make an autonomous weapon, the Chimera. The extent of its power is unclear, but when it broke free of its controls it wiped out the Lanthian civilization.
Tepoz gave Monica the 10,500BC apocalypse in a nutshell: "Those poor girls erased that entire civilization from the surface of the planet. Men, women, children, everything. The combined anger, hatred, and fear they experienced was let loose on anything that moved."
According to legend, the chimera is a creature with the body of a lion, a fire-breathing goat's head arising from its back, and tail ending in a dragon's head. Wapsi Square has rarely shown the combined form; it's appeared like a bat-winged lion. The classical description fits what we have seen of the Golem Girls, however; Brandi can take the form of a giant cat, Bud a goat, and Jin a serpent.
Roughly 1450 years ago the Chimera was split into three parts, freeing the souls within to resume their existance as the young women who they once were, more or less, and Tepoz was appointed their keeper. See the Golem Girls entry and the articles for Brandi, Bud, and Jin as individuals.