Matei or Mateiu Grigore Ghica (Albanian: Matei Gjika; Greek: Ματθαίος Γκίκας, romanized: Matthaios Ghikas; Romanian Cyrillic and Church Slavonic: Матею Гика; Turkish: Matei Gika; French: Mat[t]hieu Ghika; c. 1720 – after 1777) was the Prince of Wallachia between 4 September 1752 and June 1753, and Prince of Moldavia between June 1753 and 19 February 1756. A member of the Ghica family, he was the son of Grigore II Ghica, grandson of Alexander Mavrokordatos the Exaporite, and brother of Scarlat Ghica; he thus belonged to the Phanariotes, a group of Greek-speaking and Christian aristocrats who performed political and bureaucratic services for the Ottoman Empire. During Matei's childhood and youth, Grigore, having served as Chief Dragoman, had similarly moved between the throne of the two Romanian-speaking tributary principalities. Matei himself was first attested with his father in Moldavia, where he is known to have been homeschooled in Greek during the late 1720s. He fled that country during the Russo-Turkish War of 1735–1739, after which Grigore lost his throne and his political influence.

In the 1740s, as Grigore reemerged from exile and took the throne of Wallachia, Matei was fated for political advancement. He became Chief Dragoman at the court of Sultan Mahmud I in 1751, but was completely uninterested in the office, leaving it to be run by his father-in-law, George Bassa Mihali. He allegedly disappointed his father, who, before his death in 1752, pleaded to be succeeded by Scarlat; Matei outmaneuvered his brother, and obtained the throne for himself. He continued some of his father's policies, including when it came to expanding Bucharest, but also angered the native boyars, as well as many commoners, by flagrantly indulging the Greek community. He was forced out of the country by an uprising that earned support from the Wallachian Orthodox Church; Mahmud instead assigned him as ruler of Moldavia, moving the Moldavian prince, Constantin Racoviță, to Wallachia.

In his significantly longer period as Moldavian ruler, Matei placated the local boyardom to the point of being identified as its instrument. He was primarily focused on expanding his activities as a patron (ktitor) of the Eastern Orthodox Church, and on repairing the princely court of Iași. He spied on the Polish–Lithuanian Commonwealth, which was Moldavia's powerful neighbor, and, during his last days on the throne, lavishly entertained a caravan of Polish diplomats. Matei's ouster from that role signaled personal disaster, rendered acute when he divorced Lady Smaranda. He withdrew from high-politics until 1777, when he made an ill-fated attempt at recovering the Wallachian throne; he was part of a conspiracy which had marginal support from the Russian Empire, and, though he simply walked away from the affair, he saw his supporters severely punished by the Sublime Porte. He died at an unknown date, leaving only a daughter, who returned to Moldavia.

The Ghica family was ultimately of Albanian origin. It was first attested c. 1600 at Köprülü or Ioannina, before becoming intertwined with the Phanariote aristocracy in Istanbul. A late-18th-century account by the Wallachian boyar Matei Cantacuzino described the Ghicas as first entering Moldavia with Matei Ghica's paternal great-great-grandfather, Grigore, who traded there in the 1630s. This was during the reign of Vasile Lupu, who made him a Postelnic and a permanent envoy to the Sublime Porte (Kapucu). His son, known as Grigore I Ghica, became Prince of Wallachia in the 1660s, as the first of the dynasty to ascend to the throne of either principality; his wife Maria was from the Sturdza family, which belonged to Moldavia's boyardom. Their son, also named Matei, had only served as Dragoman, in 1727. His wife, and Matei Jr's grandmother, was Princess Roxana or Roxandra, a member of the Mavrokordatos family and daughter of Alexander the Exaporite. The two Mateis are sometimes confused, leading some authors to describe Roxana, a highly educated woman, as Matei Jr's wife (on the basis of this identification, she is called the first female physician in Romanian history).

Clan records indicate that Matei Jr himself was born in 1728 as the oldest child of Grigore II, who was had served as Dragoman of the Porte and had begun his first reign in Moldavia, and his wife Zoe "Zoița" Manos, daughter of the physician-philosopher Michail Manos. Museologist Colette Axentie describes her as Greek, noting that she was "beautiful, intelligent, and energetic." The progeny also included (in reported chronological order): George, Grigore, Smaragda, and Scarlat. The details of his birth and age are contested by other sources. In their 1727–1730 letters to Chrysanthus Nottara, both Grigore and Zoe refer to their several children as growing up. One of the sons is mentioned therein as Chrysanthus' godson, and they are all revealed to have been educated in Iași by the monk Ioannikios. In late 1727 and early 1728, the entire family, including Roxana, was attested in Hotin Fortress, then at Iași—except for the ruler, who was fighting the Budjak Horde in Tigheci.

One Wallachian manuscript reports that Matei was "aged thirty" in 1752; an inventory of other sources also shows that he was believed to have been aged 23, 25, or 27 that same year. Confusion endures as to Matei and Scarlat's respective positions in the family, with some contemporaries such as Ianache Văcărescu and Atanasiu Comnen Ipsilanti, as well as modern historians such as Gheorghe Diaconu, reporting that Scarlat was the older brother. Similarly, their exact status in respect to the principalities is a topic of contention: while technically included among the Phanariotes, and therefore perceived as oppressive foreigners, they are believed by historian Panait I. Panait to have actually been "already naturalized" in the two countries as children or youths, along with much of their family. By contrast, Axentie describes their father as "almost completely Hellenized". Highly proficient in Greek, Ottoman Turkish, and several European languages, he had learned to speak Romanian, in its Moldavian dialectal form, as early as 1726.

Of the Ghica boys, only Matei and Scarlat were likely alive during the Russian occupation of 1735–1739, which chased the family, as well as all of Moldavia's leading boyars, out of Iași. Essayist Kelemen Mikes, who was present in Iași in August 1739, wrote that Grigore "has left the city" in the wake of a likely Cossack raid, while Matei and Scarlat "are nowhere to be found." Closely affiliated with the court, Ipsilanti added that Grigore had fled for safety in Galați, and had sent one of his sons deep in Ottoman territory, at Isaccea. The reigning Sultan, Mahmud I, ordered Grigore to relinquish his throne in September 1741, but he reportedly continued to regard himself as "always and all times a Prince". Grigore's brother and successor as Dragoman, Alexander Ghica, who had angered Mahmud during the negotiations at Belgrade, was put to death in 1741. Matei, his nephew, inherited his pew in St. George's Cathedral.

In 1747, after a brief banishment to Tenedos, Grigore began his third rule over Moldavia. However, the Ghicas were by then set on obtaining control of Wallachia. A hostile account by Mihai Cantacuzino places Matei in Istanbul, where he was currying favor for his father by denouncing Wallachia's ruler, Constantine Mavrocordatos. According to this source, Matei reported on how Constantine had allowed young boyars, including Răducanu Cantacuzino, to leave for the Republic of Venice; ostensibly, they were there to study, but they also apparently took with them part of the princely treasury, for safekeeping—something which the Porte could not accept. Only nine months into his Moldavian reign, having also generously bribed the Ottoman treasurer (Hazinedar Süleyman), Grigore was granted the Wallachian throne. Both Matei and Scarlat eventually followed Grigore to Bucharest, each using the title of Beizadea—indicating their status as aspirant Princes. The Ghicas as a whole were unusually frugal, inhabiting Mihai Vodă Monastery (their nominal palace, Curtea Veche, having by then fallen into disrepair), and sometimes a small house in Pantelimon. The monarch and his two sons are painted together in a mural at Mărcuța Church, also located in Pantelimon; the junior princess, Smaragda, died at some point before 1750, leaving a daughter.