In zoology, a chimera is an animal which has (at least) two different populations of cells, which are genetically distinct and which originated in different zygotes (fertilized eggs). Chimeras are named after the mythological creature Chimera.

In Greek Mythology, Chimera (Greek Χιμαιρα [Khimaira]; Latin, Chimæra) was one of the offspring of Typhon and Echidna.

Descriptions of her vary – some say she had the body of a goat, the hindquarters of a snake or dragon and the head of a lion, though others say she had heads of both the goat and lion, with a snake for a tail. All descriptions, however, agree that she breathed fire from one or more of her heads.

Her offspring by Orthros were the Sphinx and the Nemean Lion.

Chimera was finally defeated by Bellerophon with the help of Pegasus, the winged horse, at the command of King Iobates of Lycia. There are varying descriptions of her death – some say merely that Bellerophon ran her through on his spear, whereas others say that he fitted his spear point with lead that melted when exposed to Chimera's fiery breath and consequently killed her.

The myths of the Chimera can be found in Apollodorous' Library (book 1), Virgil's Aeneid (book 6), Homer's Iliad (book 6), Ovid's Metamorphoses (book 4) and Hesiod's Theogony.

Χιμαιρα (chimaira) is Greek for "billygoat" : behind the myth may be a real battle against a war-leader or bandit whose name or title or symbol was 'Billygoat'.

The term "chimera" or "chimeric" is often used metaphorically to describe things that have combined attributes from different sources. In genetics, for example, an organism or tissue created from two or more different genetic sources is called chimeric, as in transplant patients with organs from other donors.