Theosebia, also known as Theosebia the Deaconess is a 4th century Christian leader recognized as a saint in the Eastern Orthodox Church. As a saint she is referred to as Blessed Theosebia the Deaconess. Her life and identification is ambiguous: her years of birth and death are uncertain (probably subsequent to 381). However, she is thought to have played an important role in the church in Nyssa, where she was called diaconissa, the deaconess or wife of a deacon.