Mahanayaka theros are high-ranking Buddhist monks who oversee and regulate the Buddhist clergy in Theravada Buddhist countries. The title Maha Nayaka translates to English as 'Great Leader' and it is considered to be a very important position held by a monk in a Theravada Buddhist country. It is usually bestowed upon the senior Buddhist monks who are appointed the chief prelates of monastic fraternities known as Nikayas.

The Amarapura Nikaya was a Sri Lankan monastic fraternity founded in 1800. It is named after the city of Amarapura, Burma, the capital of the Konbaung dynasty of Burma at that time. Amarapura Nikaya monks are Theravada Buddhists. On 16 August 2019, the Amarapura and Ramanna Nikaya were unified as the Amarapura–Rāmañña Nikāya, making it the largest Buddhist fraternity in Sri Lanka.