Bellur Krishnamachar Sundararaja Iyengar (14 December 1918 – 20 August 2014), better known as B.K.S. Iyengar, was the founder of the style of yoga known as "Iyengar Yoga" and was considered one of the foremost yoga teachers in the world. He was the author of many books on yoga practice and philosophy including Light on Yoga, Light on Pranayama, Light on the Yoga Sutras of Patanjali, and Light on Life. Iyengar was one of the earliest students of Tirumalai Krishnamacharya, who is often referred to as "the father of modern yoga". He has been credited with popularizing yoga, first in India and then around the world.