Namesakes
Roman and Byzantine Emperors:
3 emperors
Emperor Flavius Valentinianus (a.k.a. Valentinian) 364-375 
Emperor Flavius Valentinianus (a.k.a. Valentinian) 375-392
Emperor Flavius Placidius Valentinianus (a.k.a. Valentinian) 425-455
Saints:
1 saint
Saint Valentinian ?-500