Sun Lu-t'ang or Sun Lutang (1860-1933) was a renowned master of Chinese neijia (internal) martial arts and was the progenitor of the syncretic art of Sun-style t'ai chi ch'uan. He was also considered an accomplished Neo-Confucian and Taoist scholar (especially in the I Ching), and was a distinguished contributor to the theory of internal martial arts through his many published works.
He was born in Hebei and was named Sun Fuquan (孫福全) by his parents. Years later, his Baguazhang teacher Cheng Tinghua (程延華) gave him the name Sun Lutang. (It was common in old China for people to have multiple names). He continued to use his original name in some areas, including the publishing of his books.
LuTang and other Taijiquan studied and influenced alongside Chen Style Bajiquan helped shape the neijia aspect of Bajiquan.