Mesrop Mashtots (listen^ⓘ; Armenian: Մեսրոպ Մաշտոց, romanized: Mesrop Maštoc' 362 – 17 February 440 AD) was an Armenian linguist, composer, theologian, statesman, and hymnologist. He is venerated as a saint in the Armenian Apostolic Church.

He is best known for inventing the Armenian alphabet c. 405 AD, which was a fundamental step in strengthening Armenian national identity. He is also considered to be the creator of the Caucasian Albanian and, possibly, the Georgian script, though it is disputed.

The chief sources for the life and work of Mashtots are Koriun, Ghazar Parpetsi, and Movses Khorenatsi. The Life of Mashtots (Վարք Մաշտոցի), a hagiography by Koriun, a disciple of Mashtots, is the primary and most reliable source. The oldest fragments of the incomplete The Life manuscript are dated 12th century and are kept in Paris's Bibliothèque nationale (Arm. 178), two shorter versions of The Life dated to middle of the 14th century and one longer version of The Life is dated to the late 17th century. Hrachia Acharian, who authored the most comprehensive study on Mashtots and the Armenian alphabet, defended Koriun's work as the only accurate account. It was commissioned by Catholicos Hovsep I [hy], also a student of Mashtots, and written c. 443–450/451. The work has two versions: long and short. The former is considered by most scholars to be the original. Parpetsi and Khorenatsi largely relied upon Koriun's work. The oldest extant manuscript of Koriun's Life of Mashtots has been dated to the 12th century. It was first printed in Armenian by the Mekhitarists in San Lazzaro degli Armeni, Venice in 1833, and has been translated thrice into Modern Armenian and several foreign languages.

While Koriun, his chief biographer, only refers to him as Mashtots, Movses Khorenatsi and later Armenian historiography predominantly calls him Mesrop. It was not until the 20th century that he came to be referred to by both names, sometimes spelled with a hyphen. Some scholars, including Malachia Ormanian, maintain that Mashtots was his birth name, while Mesrop was his ecclesiastical name by which he was ordained. Anton Garagashian [hy] believed the opposite to be true. According to James R. Russell, Mashtots was his primary name, while Mesrop a secondary one, "possibly an epithet."

The etymologies of both Mesrop and Mashtots have been widely debated. In his authoritative dictionary of Armenian names, Hrachia Acharian described Mashtots to be of uncertain origin. Nicholas Adontz believed it stemmed from Iranian mašt (from mazd), which is also the origin of the name Mazdak. Asatur Mnatsakanian [hy] suggested an origin from the name of the Urartian goddess Bag-Mashtu. Russell argued that the original form of Mashtots may have been Maždoc‘, originated from Middle Parthian mozhdag and means "bearer of good news or reward". Today, Mesrop (Mesrob) is a common male name and Mesropyan (Mesrobian) a common last name among Armenians.

There is more agreement about Mesrop. Acharian considered it to be of unknown origin, but noted that it is usually thought to have originated from "serovbe", Armenian for "seraph", a word of Biblical Hebrew origin. Russell described Mesrop a mysterious word, seemingly Syriac, "perhaps an epithet meaning 'seraphic'." Some scholars maintain that Mesrop is a blend of "Mar" ("lord" in Syriac) and "Serob", a version of "Serovbe".

The date of birth of Mashtots is not well-established, but recent scholarship accepts 361. Others give 361–364 as the likely range. He was born in the village of Hatsekats (Հացեկաց) in the canton of Taron, to a father named Vardan, who may have been a priest or a nobleman. Some scholars believe he was affiliated with the Mamikonian dynasty since Taron was their feudal domain. Others suggest he may have belonged to the lesser nobility or reject his noble origin at all. Leo believed he was the son of a peasant. According to Anania Shirakatsi, Vardan was an azat. Some scholars, including Stepan Malkhasyants, have identified Vardan with Vrik, mentioned by Pavstos Buzand. Vrik was the illegitimate son of Catholicos Pap (not King Pap), the grandson of Gregory the Illuminator (through Husik). Mashtots, thus, may have been a second cousin to Catholicos Sahak Partev. Acharian outright rejected this theory, but it has been cited by Elizabeth Redgate. Other scholars, including Ormanian, believed Mashtots was the son of Vardan Mamikonian (not the better known one), the older brother of sparapet Vasak Mamikonian [hy]. This theory has been rejected by Hakob Manandian and Garnik Fntglian. James R. Russell writes that Mashtots' father was "probably a member of the Mamikonean clan."

Another point of contention is whether Mashtots was a student of Nerses the Great, first mentioned by Khorenatsi. Both Acharian and Leo rejected it. Acharian noted that Mashtots probably studied at the prominent Surb Karapet Monastery, not far from his birthplace. Koriun tells that Mashtots received "Hellenic education," i.e. education in the Greek language. Besides his native Armenian, Mashtots knew Greek, Persian (Middle Persian), and Syriac (Aramaic).