Byzantine coins are coins minted in the Byzantine Empire, also known as the Eastern Roman Empire. The Byzantine Empire existed from 330 AD to 1453 AD and encompassed much of the eastern Mediterranean, including Greece, Anatolia, Egypt, and Syria. 

The coins were often made of gold, silver or bronze and bore the portrait of the ruling emperor as well as various Christian symbols and inscriptions. They were used as a means of payment in trade and commerce and played an important role in the spread of Byzantine culture and Christianity in Europe and the Middle East. 

Many Byzantine coins have survived to the present day and are appreciated by collectors and historians alike as they offer insights into the political, economic and cultural developments of the Byzantine Empire.

From 330 to 1453, Byzantium (later also Constantinople), originally founded as Nova Roma (Νέα ̔Ρώμη), was on the one hand the residence of the emperors of the Eastern Roman Empire. On the other hand, Byzantium formed an important bridge between the cultures of the medieval Orient and Occident due to its location on the Bosporus. At the latest since the "Oriental Schism" of 1054, the city was also the center of the Orthodox Church. 

The coinage history of the Byzantine Empire begins with the coinage reforms carried out around 500 by Emperor Anastasius I (491-518), which were further expanded by Justinian I (527-565) and which essentially remained valid until the 8th century. The coinage of Byzantium was trimetallic with three nominals in gold (solidus, semis and triens), two in silver (miliarense and siliqua) and five in copper (40, 20, 10, 5 and 1 nummus). In the 7th century, the number of mints for Byzantine coins was greatly reduced. Besides Constantinople, Rome, Ravenna, Carthage and Syracuse still minted until these cities were gradually lost to the Lombards and Arabs. This opens up a wide range of types, mints and denominations of Byzantine coins to the collector.

Byzantine coinage was radically changed in 1092 under Emperor Alexios I Komnenos (1081-1118). From then on there were four coin denominations in Byzantium (hyperperon and electron trachy in gold, stamenon in a silver-copper alloy and tetarteron in copper), with the gold and silver coins being bowl-shaped (so-called skyphate). The meaning of this embossing technique, which was not always particularly successful, has not yet been completely deciphered. Possibly, it was intended to serve the simple distinction of old (minted from fine silver/finished gold) and new (consisting of alloys) coins from Byzantium.

In 1204, Constantinople was conquered by a Crusader army during the Fourth Crusade and the Latin Empire (1204-1261) was established. The Byzantine emperors moved to Nicaea for this period. From the end of the 13th century until the conquest of the city by the Ottomans under Sultan Mehmed II (1444-1446/1451-1481) on May 29, 1453, almost only Byzantine silver coins (basilicon or stavraton) similar to the European penny were minted. At the time when gold coinage was just beginning again in the rest of Europe, it was stopped in Byzantium. Yet Byzantine gold coins, with their portraits of rulers and depictions of Christ, had been a kind of "world currency of the Middle Ages" until the 11th century, when they were superseded by Italian coinage.

The most valuable Byzantine coin is the gold coin of Empress Theodora (reigned 1055-1056 AD), known as "Histamenon Nomisma". It is a rare gold coin, minted in very limited quantities and highly sought after for its historical significance and rarity. 

The coin bears the portrait of Theodora on the obverse and the image of the Virgin Mary on the reverse, with the inscription "Mother of God, help your servant Theodora". The coin is known for its exceptional quality and deep relief. In 2020, such a coin was sold at auction for about $3.3 million, making it the most expensive Byzantine coin to date.