Chimera – sometimes depicted with the heads of a goat and a lion. The Lernaean Hydra – an ancient nameless serpent-like chthonic water beast that possessed numerous heads. Orthrus – a two-headed dog owned by Geryon. Scylla – sometimes described as a six-headed sea monster.Other multi-headed creatures in Greek mythology include:

The Hecatonchires – giants with fifty heads and one hundred arms. The word "Hecatonchire" means "hundred arms". They were the sons of Gaia, and Uranus. Hecate – Greek goddess of witches, nightmares, crossroads, and one of the Moon deities; sometimes represented with three heads. Iranian mythology
Zahhak, an evil figure in Iranian mythology - also evident in ancient Iranian folklore as Aži Dahāka (Azh dahak) - is the most significant and long-lasting of the ažis of the Avesta, the earliest religious texts of Zoroastrianism. He is described as a monster with three mouths, six eyes, and three heads (presumably meaning three heads with one mouth and two eyes each), cunning, strong and demonic. But in other respects Aži Dahāka has human qualities, and is never a mere animal. Hinduism
Hindu deities are often depicted with multiple arms or heads. The fire-god Agni has two heads
Dattatreya: three
The creator-god Brahma: four
The goddess Gayatri: five
The war-god Kartikeya: sixThough usually depicted with one head, some deities like Ganesha (in Heramba form) and Shiva (Sadashiva) have aspects where they are depicted with multiple heads; five in this case. The Vishvarupa form of Vishnu is described as having infinite heads. Besides deities, demons (asura and rakshasa) may be depicted with multiple heads.
Focal dystonia, or focal task specific dystonia, is a neurological condition, a type of dystonia, that affects a muscle or group of muscles in a specific part of the body during specific activities, causing involuntary muscular contractions and abnormal postures. There are many different types of focal dystonia, each effecting a different region of the body. For example, in focal hand dystonia, or writers cramp, the fingers either curl into the palm or extend outward without control. In musicians, the condition is called musicians focal dystonia, or simply, musicians dystonia. In sports, it may be involved in what is commonly referred to as the yips. The condition appears to be associated with over-training, and individualized treatment strategies may involve medications, retraining techniques, and procedures. Signs and Symptoms
People with dystonia experience tightness, cramping, fatigue, involuntary sustained or repetitive muscle contractions that can be painless or painful and resulting in abnormal posturing, twisting motions, and even tremors. Focal dystonia typically presents in adults, more commonly in women ranging from ages 30 through 40. Major types of focal dystonia affect the limbs, face, mouth, neck, and larynx. These focal dystonias can be exclusive to specific tasks, like writing or playing an instrument. Focal dystonia will typically have a subtle and slow onset before slowly worsening over years. During the beginning stages, symptoms can be intermittent and without clear associations and provocation. The progression of this disease can vary from person to person.