Kroni (Tamil: குறோணி) is a figure in Ayyavazhi mythology. He is the primordial manifestation of evil, and manifests in various forms of evil, such as Ravana and Duryodhana, in different ages or yugas. In order to counteract and destroy the evil of Kroni's manifestations, Mayon (a Tamil name for Vishnu) incarnates as Avatars such as Rama and Krishna. Kroni is analogous to Satan in the Judaeo-Christian tradition. He shares many similarities with the demon Kali of the Mahabharata and Kalki Purana.
According to the Akilattirattu Ammanai, the Ayyavazhi holy book, Kroni was born in the first of the Eight Yukams (Yuga (Sanskrit); Aeons ((English)) with multitudinous limbs each the size of a mountain, and was the first evil to be born in the Universe. He had a fire of ravenous hunger in his stomach, and he drank all the waters of the sea to quell it. When the water was insufficient, he then swallowed Kailayam (Kailash), the abode of Shiva, and then proceeded to devour the entire Universe. Mayon, residing with Shiva in Kailayam, escaped promptly and undertook a Tavam (Tapas (Sanskrit); Penance (English)) to receive a boon from Shiva in order to destroy Kroni. Shiva granted the boon, but made Mayon aware of the necessity of appearing in different forms for the successive six yukams in order to destroy the six fragments of Kroni. Being aware of the mission, Mayon sliced Kroni into six fragments and saved the Universe. With that event the first Yukam came to an end.