William Pinkney (April 17, 1810 – July 4, 1883) was fifth bishop of the Episcopal Diocese of Maryland.
He was born in Annapolis, Maryland and attended St. John's College, Annapolis, from which he graduated at age 17. He studied law under his uncle, Severus Pinkney, and was admitted to the bar, but never practiced. Instead, influenced by his mother, a devout Methodist, in 1831 he entered Princeton Theological Seminary in New Jersey to study for the ministry. Financial and family circumstances forced his withdrawal two years later, and Pinkney became a tutor to the family of John Neville Steele, a devout Episcopalian in Dorchester County, Maryland. He decided to apply for holy orders with that denomination.
He married Miss Elizabeth Lowndes, from a prominent family in Prince George's County, on October 2, 1838.
Maryland's bishop, the Right Reverend William Murray Stone ordained Pinkney to the diaconate on April 12, 1835, and to the priesthood the following year. Rev. Pinkney was initially assigned to Somerset and Coventry parishes on the Eastern Shore, but his health soon failed. He then became as rector of St. Matthew's Episcopal Church in Hyattsville, Maryland (formerly known as Addison's Chapel) and its chapel of ease Zion Parish. During his leadership of those parishes, which lasted until 1857, Rev. Pinkney secured the rebuilding of both churches. St. Matthew's congregation moved to a larger Gothic-style frame building in Bladensburg, Maryland in 1844, which was consecrated in 1856. St. John's Episcopal Church, Zion Parish (which had once been the lower chapel of that parish and burned down in 1845), was rebuilt and consecrated in 1856. After getting both congregations onto solid footings and declining a call from the Church of the Epiphany (Washington, D.C.), Rev. Pinkney finally decided to move into Washington, D.C. and serve as rector of the Church of the Ascension.