The Germanic peoples were tribal groups who lived in Northern Europe during Classical antiquity and the Early Middle Ages. In modern scholarship, they typically include not only the Roman-era Germani who lived in both Germania and parts of the Roman Empire, but also all Germanic speaking peoples from this era, irrespective of where they lived, most notably the Goths. Another term, ancient Germans, is considered problematic by many scholars because it suggests identity with present-day Germans. Although the first Roman descriptions of Germani involved tribes west of the Rhine, their homeland of Germania was portrayed as stretching east of the Rhine, to southern Scandinavia and the Vistula in the east, and to the upper Danube in the south. Other Germanic speakers, such as the Bastarnae and Goths, lived further east in what is now Moldova and Ukraine. The term Germani is generally only used to refer to historical peoples from the 1st to 4th centuries CE.

Different academic disciplines have their own definitions of what makes someone or something "Germanic". Some scholars call for the term's total abandonment as a modern construct, since lumping "Germanic peoples" together implies a common group identity for which there is little evidence. Other scholars have defended the term's continued use and argue that a common Germanic language allows one to speak of "Germanic peoples", regardless of whether these ancient and medieval peoples saw themselves as having a common identity. Scholars generally agree that it is possible to refer to Germanic languages from about 500 BCE. Archaeologists usually associate the earliest clearly identifiable Germanic speaking peoples with the Jastorf culture of the Pre-Roman Iron Age in central and northern Germany and southern Denmark from the 6th to 1st centuries BCE. This culture existed around the same time that the First Germanic Consonant Shift is theorized to have occurred, leading to recognizably Germanic languages. Germanic languages expanded south, east, and west, coming into contact with Celtic, Iranic, Baltic, and Slavic peoples before they were noted by the Romans.

Roman authors first described the Germani near the Rhine in the 1st century BCE, while the Roman Empire was establishing its dominance in that region. Under Emperor Augustus (27 BCE – 14 CE), the Romans attempted to conquer a large part of Germania between the Rhine and Elbe, but withdrew after their shocking defeat at the Battle of the Teutoburg Forest in 9 CE. The Romans continued to manage the Germanic frontier carefully, meddling in cross-border politics, and constructing a long fortified border, the Limes Germanicus. From 166 to 180 CE, Rome was embroiled in a conflict against the Germanic Marcomanni and Quadi with their allies, which was known as the Marcomannic Wars. After this major disruption, new groupings of Germanic peoples appear for the first time in the historical record, such as the Franks, Goths, Saxons, and Alemanni. During the Migration Period (375–568), such Germanic peoples entered the Roman Empire and eventually established their own "barbarian kingdoms" within the territory of the Western Roman empire itself. Over time, the Franks became the most powerful of them, conquering many of the others. Eventually, the Frankish king Charlemagne claimed the title of Holy Roman Emperor for himself in 800.

Archaeological finds suggest that Roman-era sources portrayed the Germanic way of life as more primitive than it actually was. Instead, archaeologists have unveiled evidence of a complex society and economy throughout Germania. Germanic-speaking peoples originally shared similar religious practices. Denoted by the term Germanic paganism, they varied throughout the territory occupied by Germanic-speaking peoples. Over the course of Late Antiquity, most continental Germanic peoples and the Anglo-Saxons of Britain converted to Christianity, but the Saxons and Scandinavians converted only much later. The Germanic peoples shared a native script—known as runes—from around the first century or before, which was gradually replaced with the Latin script, although runes continued to be used for specialized purposes thereafter.

Traditionally, the Germanic peoples have been seen as possessing a law dominated by the concepts of feuding and blood compensation. The precise details, nature and origin of what is still normally called "Germanic law" are now controversial. Roman sources state that the Germanic peoples made decisions in a popular assembly (the thing) but that they also had kings and war leaders. The ancient Germanic-speaking peoples probably shared a common poetic tradition, alliterative verse, and later Germanic peoples also shared legends originating in the Migration Period.

The publishing of Tacitus's Germania by humanist scholars in the 1400s greatly influenced the emerging idea of "Germanic peoples". Later scholars of the Romantic period, such as Jacob and Wilhelm Grimm, developed several theories about the nature of the Germanic peoples that were highly influenced by romantic nationalism. For those scholars, the "Germanic" and modern "German" were identical. Ideas about the early Germans were also highly influential among members of the nationalist and racist völkisch movement and later co-opted by the Nazis. During the second half of the 20th century, the controversial misuse of ancient Germanic history and archaeology was discredited and has since resulted in a backlash against many aspects of earlier scholarship.

The etymology of the Latin word Germani, from which Latin Germania and English Germanic are derived, is unknown, although several proposals have been put forward. Even the language from which it derives is a subject of dispute, with proposals of Germanic, Celtic, Latin, and Illyrian origins. Herwig Wolfram, for example, thinks Germani must be Gaulish. The historian Wolfgang Pfeifer more or less concurs with Wolfram and surmises that the name Germani is likely of Celtic etymology and is related to the Old Irish word gair ('neighbours') or could be tied to the Celtic word for their war cries, gairm, which simplifies into 'the neighbours' or 'the screamers'. Regardless of its language of origin, the name was transmitted to the Romans via Celtic speakers.

It is unclear whether any people group ever referred to themselves as Germani. By late antiquity, only peoples near the Rhine, especially the Franks and sometimes the Alemanni, were called Germani or Germanoi by Latin and Greek writers respectively. Germani subsequently ceased to be used as a name for any group of people and was revived as such only by the humanists in the 16th century. Previously, scholars during the Carolingian period (8th–11th centuries) had already begun using Germania and Germanicus in a territorial sense to refer to East Francia.