Shankaracharya, (IAST: Śaṅkarācārya, Shankara acharya) is a commonly used title of heads of mathas in the Advaita Vedanta tradition. The title derives from Adi Shankara, a 9th century CE reformer of Hinduism. He is honored as Jagadguru, a title that was used earlier only to Lord Krishna. The popular view among historians is that there were four mathas established by Ādi Śankara:

Sri Adi Shankara established a fifth math in Kanchipuram, with jurisdiction over the four mathas and that Sankaracharya ascended a sarvagna-pitha at Kanchipuram and he died in Kanchi.^{[citation needed]}

Like other religions and sects, some rivalry exists between some groups who claim to have been initiated into the Shankaracharya Order.

The existence of such multiple mathas occurs because a Guru/or descendant of the shankaracharya lineage could have had many disciples. This could have resulted in the branching out of the parent institution. It is also possible that a Guru might have died without naming a successor, leading to the formation of rival groups.

Adi Shankara (Sanskrit: आदिशङ्करः Ādi Śaṅkara, pronounced [aːd̪i ɕəŋkəɾə]) (788 CE - 820 CE), also known as Śaṅkara Bhagavatpādācārya and Ādi Śaṅkarācārya was an Indian sage from Kalady in present day Kerala who consolidated the doctrine of advaita vedānta. His teachings are based on the unity of the ātman and brahman— non-dual brahman, in which brahman is viewed as nirguna brahman, brahman without attributes.

Shankara travelled across the Indian subcontinent to propagate his philosophy through discourses and debates with other thinkers. He is reputed to have founded four mathas ("monasteries"), which helped in the historical development, revival and spread of Advaita Vedanta of which he is known as the greatest revivalist. Adi Shankara is believed to be the organizer of the Dashanami monastic order and the founder of the Shanmata tradition of worship.

His works in Sanskrit concern themselves with establishing the doctrine of advaita (nondualism). He also established the importance of monastic life as sanctioned in the Upanishads and Brahma Sutra, in a time when the Mimamsa school established strict ritualism and ridiculed monasticism. Shankara represented his works as elaborating on ideas found in the Upanishads, and he wrote copious commentaries on the Vedic canon (Brahma Sutra, principal upanishads and Bhagavad Gita) in support of his thesis. The main opponent in his work is the Mimamsa school of thought, though he also offers arguments against the views of some other schools like Samkhya and certain schools of Buddhism.

Zakir Abdul Karim Naik (Urdu: ذاکر عبدالکریم نائیک; born 18 October 1965) is an Indian public speaker on the subject of Islam and comparative religion. He is the founder and president of the Islamic Research Foundation (IRF), a non-profit organisation that owns the Peace TV channel based in Dubai, UAE. He is sometimes referred to as a televangelist. Before becoming a public speaker, he trained as a doctor. He has written two booklets on Islam and comparative religion. He is regarded as an exponent of the Salafi ideology; he places a strong emphasis on individual scholarship and the rejection of "blind Taqlid", which has led him to repudiate the relevance of sectarian or Madh'hab designations, all the while reaffirming their importance.

Zakir Abdul Karim Naik was born on 18 October 1965 in Mumbai, India. He attended St. Peter's High School in Mumbai. Later he enrolled at Kishinchand Chellaram College, before studying medicine at Topiwala National Medical College and Nair Hospital and later the University of Mumbai, where he obtained a Bachelor of Medicine and Surgery (MBBS). His wife, Farhat Naik, works for the women's section of the IRF.