Protasius (anglicized Protase) may refer to:

• Protasius (martyr)
• Protasius (bishop of Milan), reigned 328–343, saint
• Protasius, an archbishop of Tarragona in 637–646
• Protasius (bishop of Lausanne) [fr] (died c. 650)
• Protasius of Boskowitz and Černahora [cs] (died 1482), bishop of Olomouc