Kali is considered to be the destroyer of evil spirits and the preserver of devotees. She is the consort of Shiva. Her name apparently derives from the word 'kala' (Sanskrit for 'time' or 'dark').
Often depicted with four arms and a necklace of skulls, she brandishes various death related implements. Skulls, cemeteries, and blood are associated with her worship. Despite this, she is a highly reputable deity in India.
Her poor reputation in the West came from the cult of the Thuggee, Muslims who took the goddess Kali as their deity. They robbed and murdered travellers and were destroyed by the British.