Namesakes
Roman and Byzantine Emperors:
4 emperors
Emperor Constantinus Ducas (a.k.a. Ducas) 1059-1067 
Emperor Michael Ducas (a.k.a. Ducas) 1071-1078
Emperor Alexius Ducas Murtzuphius (a.k.a. Ducas) 1204
Emperor Johannes Ducas Vatatzes 1221-1254
Saints:
1 saint
Saint John Ducas Vatatzes 1192-1254