Mai Dusi (1796-1857), whose original name was Walter Henry Medhurs, was a priest of London Missionary Society of British Christianity, and the earliest Christian missionary who came to China. He became a Christian follower at the age of 14. In 1817, he went to India, where he began to learn Chinese. In 1819 he got the priest qualification in Malacca.

Before 1842, his activities were mainly in Southeast Asia. After China's failure in Opium War in 1842, many priests active in Southeast Asia shifted their missionary work to Hong Kong, Shanghai and Guangzhou. In 1843 Mai Dusi moved to Shanghai and became the first foreign priest in Shanghai. Mai Dusi, who was one of the initiators of London Missionary Society Shanghai branch, made much contribution to the translation of the Bible.

In 1857 he died in Britain and left many works such as The Way to Truth, English-Chinese Dictionary, China: Present and Future, and so on.