The 1st century was the century spanning AD 1 (represented by the Roman numeral I) through AD 100 (C) according to the Julian calendar. It is often written as the 1st century AD or 1st century CE to distinguish it from the 1st century BC (or BCE) which preceded it. The 1st century is considered part of the Classical era, epoch, or historical period. The Roman Empire, Han China and the Parthian Persia were the most powerful and hegemonic states.

During this century, the Roman Empire (ruled by the Julio-Claudian and Flavian dynasties) continued to be in a period of relative stability known as Pax Romana, withstanding a financial crisis in 33 and a civil war in 69. In Europe, Rome expanded into Britain and fought wars in Germania and Dacia. In Africa, Rome was challenged by Tacfarinas, who led his own Musulamii tribe and a loose and changing coalition of other Berber tribes before being defeated in 24. In West Asia, Rome defeated a Jewish rebellion (66–73) and fought a war with Parthia from 58–63, though the latter conflict was inconclusive. In East Asia, the Chinese Western Han dynasty was overthrown and replaced by the Xin dynasty in 9, which in turn faced its own rebel movements (namely the Red Eyebrows and Lulin), and was replaced by the Eastern Han dynasty in 25. The Eastern Han dynasty then faced and quelled a rebellion by the Trưng sisters (40–43).