A vetala (Sanskrit vetāla or वेताळ) is a ghost-like being from Hindu mythology. The vetala are defined as spirits inhabiting corpses and charnel grounds. These corpses may be used as vehicles for movement (as they no longer decay while so inhabited); but a vetala may also leave the body at will.
A vetala can be a vampire, a flesh eater and blood drinker, like a skeleton with large tattered wings.
In Hindu folklore, the vetala is an evil spirit who haunts cemeteries and takes demonic possession of corpses. They make their displeasure known by troubling humans which mainly includes affection towards God and good in the person as they want them to be evil minded. In their course of action they can drive people mad by knowing the psychological defects of the person, kill children by making them mentally weak to commit suicide,and cause miscarriages.They also say it guards villages but actually they are not doing that. According to ancient secret texts available with High Priest of a family they say during old days bandits used to steal valuable treasure in the Hindu temples, so in order to protect them they made the public believe that vetalas are guarding the village which will be effective to keep the bandits away from village and believing in the same way the God will be guarding them.They also say as both the good and bad people live in this world even the vetalas are also both good and bad where bad vetalas are only extreamly dangerous and good will be servants of God.
They are hostile spirits of the dead trapped in the 'twilight zone' between life and afterlife. These creatures can be repelled by the chanting of mantras with good mind concentration. One can free them from their ghostly existence by performing their funerary rites.They pretend to have an uncanny knowledge about the past, present, and future which they communicate and manipulate the persons mind through dreams in order to control the person and a deep insight into human nature.They also communicate through thoughts which also includes images and influencing the 'Manasu'(Indian word -Thoughts of Heart) which will be highly effective.Therefore many sorcerers seek to capture them and turn them into slaves and use them for their selfish needs.
A sorcerer once asked King Vikramaditya to capture a vetala who lived in a tree that stood in the middle of a cremation ground. The only way to do that was by keeping silent. Every time Vikramaditya caught the vetala, the vetala would enchant the king with a story that would end with a question. No matter how hard he tried, Vikramaditya would not be able to resist answering the question. This would enable the vetala to escape and return to his tree. The stories of the vetala have been compiled in the book Baital Pachisi.
There is also a strong Vetala cult in the Konkan region, under the names of Betal, Vetal, etc. Since Shri Betal is said to be the brother of Shri Shantadurga. Therefore, wherever a temple of Shantadurga is, there will be a temple dedicated in honour of Shri Betal either within the temple complex of Shri Shantadurga or somewhere in the sylvan surroundings.. It seems, however, that the relation between the literary Vetala and this demigod's is feeble at best. There is a Shri Betal temple in Amona, Goa. Vetál is the worshipper (or sevak) of Kala Bhairava and is the head of all spirits and ghouls and vampires and all kinds of pisachas. He has another form which is a more potent and fiery form, that of Agni Vetal who is the sevak of none other than Kalika. Lord Agnivetal has flames on his head and controls fire. He is also known as Agya Vetal. Agnivetal is used by Tantriks to perform evil black magic on people. But it isn't Lord Agnivetal's fault because the Tantriks misuse the powers given to them on propitiating Agnivetal(rather his Daityas which are at his feet-they are the ones who accept the blood sacrifices).So, accordingly to Sacred Hindu Texts(confidential,available with only few high priests) the person can get rid of the evil spirits by chanting a Mantra- "DURGAMBA DURGAMBA DURGAA DURGAE DURGAMBA - OM NAMAHA SHIVAYA"(together as one mantram) which means mother and father of the universe please rescue me (with good mind concentration).