Maa Kali is considered the oldest form of mother worship. She is the primordial force that intrigues the ultimate consciousness, i.e., Shiva to evolve into a cosmic design together.
Maa Kali is also considered the destroyer of evil forces and instills fearlessness in her devotees.
Mahakali appears adorning the mund-maal (skull garland) which represents cycle of life and death and fierce form is the destroyer of all the evil powers.
Shamshan Kali is worshipped by Tantrics and sanyasis who seek emancipation from the cycle of death and birth
Tara Mahavidya is worshipped in tantric ways and is considered among the highest liberators. Tara Shaktipeeth is present in West Bengal.
Dakshin Kali appears in a benevolent form, like a mother with four hands, and is worshipped in Dakshineswar, Kalighat near Kolkata.
Krishna-Kali is the form which combines both Shri Krishna and Maa Kali, also considered as Draupadi. According to legends, Krishna Kali fought the Mahabharata war in the fiercest form.
Maa Kali appears in many other subtler forms which are mostly worshipped by the Tantrics and are not for the householders. Like Guhya Kali, Hamsa Kali, Kankal Kali, Adya Kali etc.