Alfred Percy Sinnett (1840–1921) was an English journalist, author, and prominent theosophist. Born in London, he was educated at the University College School. Sinnett worked as an editor for several newspapers, including The Pioneer, a leading English-language publication in British India. While in India, he met Helena Petrovna Blavatsky and Henry Steel Olcott, co-founders of the Theosophical Society, and became deeply involved in Theosophy.
Sinnett is best known for his books The Occult World (1881) and Esoteric Buddhism (1883), which introduced Western audiences to theosophical teachings and Eastern metaphysical ideas. His works were based on communications with Mahatmas (spiritual adepts) via Blavatsky and others, contributing to popular interest in Eastern spirituality and occultism during the late 19th century.
After returning to England, Sinnett continued his involvement with theosophy, serving as Vice President of the Theosophical Society and influencing its direction. His later works include The Growth of the Soul and Super-Physical Science. Sinnett remained active in spiritual and metaphysical discussions until his death in 1921.