Ayyappan, also known as Dharmasastha and Manikandan, is the Hindu deity of truth and righteousness. According to Hindu theology, he is described as the son of Shiva and Mohini (the female avatar of Vishnu), thus representing a bridge between Shaivism and Vaishnavism.

Ayyappan is a warrior deity and is revered for his ascetic devotion to Dharma, the ethical and right way of living. He is usually depicted as a youthful man riding or near a Bengal tiger and holding a bow and arrow. In some representations, he is seen holding a sword and riding an Indian elephant or a horse. Other iconography generally shows him in a yogic posture wearing a bell around his neck.

The legend and mythology of Ayyappan varies across regions, reflecting a tradition that evolved over time. According to Malayalam lore, Ayyappan is presented as a warrior prince of Pandala kingdom. In the later years, the stories of Ayyappan expanded with various versions describing him as a warrior who protected people from evil doers while helping restore Dharmic practices and he evolved to be a deity. In some regions, Ayyappan and Tamil folk deity Ayyanar are considered to be the same with similar characteristics.

Although Ayyappan worship has been prevalent earlier in Kerala, his popularity spread to most of Southern India in the 20th century. There are several temples in the region dedicated to him, the foremost of which is Sabarimala. Sabarimala is located on the banks of the Pamba river in the forests of the Western Ghats, and is a major pilgrimage destination, attracting millions annually. Pilgrims often engage in weeks of preparations in advance by leading a simpler life, remaining celibate, and trekking to the hill barefoot while carrying an irumudi (a bag with offerings) on the head.

The name Ayyappan is a combination of two words ayyan and appan. Ayyan in Tamil and the Malayalam word acchan mean "father". Appan also means "father" in Tamil, and both these words are also used as honorific titles. In Hindu texts, he is described as the son of Mohini (the female form of Vishnu) and Shiva with the name Ayyappan connoting as "lord-father". The name could have also been derived from the combination of aryan and appan with the former meaning "revered".

In Hindu scriptures such as Vishnu Purana and Srimad Bhagavatham, he is referenced as Dharmasastha and Sastha, meaning "ruler of the realm". The word Sastha could have also be derived from Buddhism as Ayyappan is seen as an incarnation of Buddha and Buddha was known by the same name, meaning "teacher". He is also known as Hariharasuthan, meaning the "son of Harihara", a fusion of Hari and Hara, the names given to Vishnu and Shiva respectively. He is also called Manikanda with mani meaning bell and kanda meaning neck in Sanskrit, and meaning the wearer of a bell on his neck.

Ayyappan is a warrior deity and is revered for his ascetic devotion to Dharma, the ethical and right way of living, deployment of his military genius and yogic war abilities to destroy those who are powerful but unethical, abusive and arbitrary. He is usually represented as a celibate young man holding a bow and arrow, and riding a Bengal tiger. In some representations, he is seen holding an upraised bow in his left hand, while holding either an arrow or sword in his right hand placed diagonally across his left thigh. Other iconography generally shows him in a yogic posture wearing a bell around his neck. In some representations, such as in Sri Lanka, he is shown riding an Indian elephant or a horse.

The legend and mythology of Ayyappan vary across regions, reflecting a tradition that evolved over time. According to the Puranas, he is mentioned as an incarnation of Hariharaputra, the son of Shiva and Mohini (female form of Vishnu). While this interaction between Shiva and Vishnu is mentioned in the Bhagavata Purana, he is not referenced by the name Ayyappan.