The Nabonidus Chronicle is an ancient Babylonian text, part of a larger series of Babylonian Chronicles inscribed in cuneiform script on clay tablets. It deals primarily with the reign of Nabonidus, the last king of the Neo-Babylonian Empire, covers the conquest of Babylon by the Persian king Cyrus the Great, and ends with the start of the reign of Cyrus's son Cambyses, spanning a period from 556 BC to some time after 539 BC. It provides a rare contemporary account of Cyrus's rise to power and is the main source of information on this period;Amélie Kuhrt describes it as "the most reliable and sober [ancient] account of the fall of Babylon."
The chronicle is thought to have been copied by a scribe during the Seleucid period (4th-1st century BC) but the original text was probably written during the late 6th or early 5th century BC. Similarities with the Nabonassar to Shamash-shum-ukin Chronicle, another of the Babylonian Chronicles, suggest that the same scribe may have been responsible for both chronicles. If so, it may date to the reign of Darius I of Persia (c. 549 BC–486 BC).
The Nabonidus Chronicle is preserved on a single clay tablet now kept at the British Museum in London. Like the other Babylonian Chronicles, it lists in an annalistic (year-by-year) fashion the key events of each year, such as the accession and deaths of kings, major military events, and notable religious occurrences. It follows a standard pattern of reporting only events of immediate relevance to Babylonia, making it of somewhat limited utility as a source for a wider history of the region. The tablet itself is fairly large, measuring 140 mm wide by 140 mm long, but is significantly damaged with its bottom and most of the left-hand side missing. The text was composed in two columns on each side, originally consisting of some 300-400 lines. What remains is extremely fragmentary; little more than 75 lines of text are still legible. The missing portions consist of most of the first and fourth columns, along with the bottom of the second and the top of the third. There appears to have been a colophon at the bottom of the tablet, but it too is largely missing.