Roman emperor Caligula accepts the titles of the Principate, bestowed on him by the Senate.

AD 37 (XXXVII) was a common year starting on Tuesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Proculus and Pontius. The denomination AD 37 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

The Roman emperor was the ruler and monarchical head of state of the Roman Empire, starting with the granting of the title augustus to Octavian in 27 BC. The term emperor is a modern convention, and did not exist as such during the Empire. When a given Roman is described as becoming emperor in English, it generally reflects his accession as augustus, and later as basileus. Another title used was imperator, originally a military honorific, and caesar, originally a cognomen. Early emperors also used the title princeps alongside other Republican titles, notably consul and pontifex maximus.

Gaius Caesar Augustus Germanicus, also called Gaius and Caligula, was Roman emperor from AD 37 until his assassination in 41. He was the son of the Roman general Germanicus and Augustus' granddaughter Agrippina the Elder, members of the first ruling family of the Roman Empire. He was born two years before Tiberius became emperor. Gaius accompanied his father, mother and siblings on campaign in Germania, at little more than four or five years old. He had been named after Gaius Julius Caesar, but his father's soldiers affectionately nicknamed him "Caligula".

The Principate was the form of imperial government of the Roman Empire from the beginning of the reign of Augustus in 27 BC to the end of the Crisis of the Third Century in AD 284, after which it evolved into the Dominate. The principate was characterized by the reign of a single emperor (princeps) and an effort on the part of the early emperors, at least, to preserve the illusion of the formal continuance, in some aspects, of the Roman Republic.