Which Roman emperors banned human sacrifice in Celtic territories?

The Roman emperors who forbade the practice of human sacrifice in Celtic territories were Tiberius and Claudius.1

While historical accounts from authors such as Cicero, Caesar, Suetonius, and Lucan confirm that human sacrifice was practiced in Gaul, and Pliny the Elder noted its occurrence in Britain, these imperial prohibitions were part of Roman efforts to suppress customs they deemed incompatible with their own cultural and legal standards.1