Mary May Scollen (1887-1967), known by her religious name as Sister Mary Justinian, was an Australian religious who was notable for her nursing and hospital administration. She joined the North Sydney congregation of the Sisters of Mercy, professing final vows in 1907. Trained as a nurse, she served as matron of the Mater Misericordis Hospital in the north Sydney area, for 44 years. She then served as hospital administrator for four years, and concurrently was the superior for her convent. She was appointed M.B.E. in 1958.