The Rt Rev William Walmsley Sedgwick (1858–1948^[1]) was the 5th Anglican Bishop of Waiapu, New Zealand, whose Episcopate spanned a 15-year period during the first half of the 20th century.

Born at Freemantle in Southampton,^[2] England, he was educated at St Martin's, York and matriculated in 1879. He attended Christ's College, Cambridge and graduated in 1882 with a B.A.^[3][4] He was ordained as a deacon at Dover in 1882, and as a priest at Canterbury in 1883.^[5] He embarked on his career with a curacy at St. John The Baptist, Wateringbury.^[6]

He was a Naval Chaplain from 1884 to 1886; he took part in the Suakin Expedition, 1884–85; and served as Chaplain on H.M.S. Thunderer in the Mediterranean Fleet, 1885–86.^[7] He held incumbencies at Hockley Heath in the West Midlands, England, 1886–89; Vryburg, British Bechuanaland, 1889–93; Bedford, Eastern Cape, 1893–96; Evershot, Dorset, 1897–98; and he became the chaplain to the Earl of Home, 1897–1900.^[8][9]

He emigrated to New Zealand and was appoint as the vicar of Waikari, 1901–03; vicar of Akaroa, 1903–04; vicar of St Luke's Church, Christchurch, 1904–14; canon of ChristChurch Cathedral, Christchurch, 1911–14; and chaplain to the Bishop of Christchurch, 1914.^[10]

On 22 February 1914 he became the Bishop of Waiapu. He retired as bishop in 1929. His last post was as Vicar of Detling, Kent, England, 1931–32.^[11] From 1938 until his death in 1948 he was licensed to officiate in the Diocese of Grahamstown, Makhanda, South Africa.^[12]