Guruvayurappan (Malayalam: ഗുരുവായൂരപ്പന്, (transliterated guruvāyūrappan)) also often written Guruvayoorappan, is a form of Vishnu worshipped mainly in Kerala. He is the presiding deity of Guruvayur temple, who is being worshiped as Shri Krishna in His child form, popularly known as Guruvayur Unnikkannan (Guruvayur baby Krishna). Even though the deity is that of chatur bahu (four-handed) Vishnu, the concept (Sankalpam) of the people is that the deity is the infant form of Lord Krishna. The deity represents the purna rupa (full manifestation) revealed by baby Krishna to His parents immediately after His advent in Kamsa’s jail. Lord Krishna immediately after his birth had revealed Himself as four-armed standing Vishnu in front of His parents Devaki and Vasudeva. So this is the reason why baby Krishna is worshipped on a Vishnu deity. The temple is located in the town of Guruvayur, Thrissur district, Kerala, India.
The word Guruvayurappan, meaning Lord of Guruvayur, comes from the words Guru (ഗുരു) referring to Brihaspati, the Guru of the Devas, Vayu (വായു), the God of Wind and Appan (അപ്പന്), meaning ‘father’ or ‘Lord’ in Malayalam. Since Guru and Vayu installed Krishna’s deity, the name Guruvayurappan was given to the deity.
It is believed that the idol of Guruvayurappan was worshipped by Vasudeva and Devaki, the parents of Krishna, and represents the full manifestation of Vishnu, and later was worshipped by Krishna, an Avatar of Vishnu Himself. The deity is made of a stone called “Patala Anjanam” or black bismuth and is in the standing pose with four arms, carrying the Panchajanya (shanku or conch), the Sudarshana Chakra (chakra or disc), the Koumodaki (gada or mace) and Padma (lotus).