| Type: | Bishop |
| Honorific Prefix: | The Right Reverend |
| William Mercer Green | |
| Honorific Suffix: | D.D. |
| Bishop of Mississippi | |
| Church: | Episcopal Church |
| Diocese: | Mississippi |
| Term: | 1938–1942 |
| Retired: | --> |
| Predecessor: | Theodore DuBose Bratton |
| Successor: | Duncan Montgomery Gray Sr. |
| Ordination: | December 9, 1900 |
| Ordained By: | Hugh Miller Thompson |
| Consecration: | May 20, 1919 |
| Consecrated By: | Daniel S. Tuttle |
| Birth Date: | 12 July 1876 |
| Buried: | Greenwood Cemetery (Jackson, Mississippi) |
| Parents: | Duncan Cameron Green & Arabella Bott |
| Spouse: | Pauline Leila Priestly |
| Children: | 3 |
| Previous Post: | Coadjutor Bishop of Mississippi (1919-1938) |
William Mercer Green (July 12, 1876 – November 12, 1942), was the 4th Bishop of Mississippi from 1938 till 1942. He was the grandson of William Mercer Green, the 1st Bishop of Mississippi.
Green attended the public schools of Greenville, Mississippi. Later he studied theology and graduated from . He also earned his Doctor of Divinity from the same university.[1]
In 1899 Green was ordained deacon and priest a year later. Most of his priesthood was spent as rector of parishes around Mississippi.[2] He also served as rector of St John's Church in Knoxville, Tennessee. He was also Dean of All Saints College in Vicksburg, Mississippi. His last post prior to his election was as rector of St Andrew's Church in Jackson, Mississippi.[3]
In 1919 Green was elected Coadjutor Bishop of Mississippi. He succeeded Bishop Theodore DuBose Bratton as diocesan bishop upon his retirement in 1938. His episcopacy was mostly focused on rural work in the diocese. Green died in office on November 12, 1942. His funeral was held on November 16 and was presided over by R. Bland Mitchell, Bishop of Arkansas.[4]