The name Isaias is a masculine given name of Hebrew origin, derived from the biblical name Isaiah. It finds its roots in the Hebrew name "Yshāyāhū," which means "Yahweh is salvation" or "the Lord is salvation."

The name first appeared in the Old Testament of the Bible, where it refers to the prophet Isaiah, one of the major prophets in Judaism and Christianity. Isaiah lived in the 8th century BCE and is believed to have prophesied about the coming of the Messiah.

In the Book of Isaiah, the prophet's name is mentioned numerous times, and his prophecies and teachings are recorded. This biblical figure's influence on the name's popularity cannot be overstated, as it became a common name among Jewish and Christian communities throughout history.

One of the earliest recorded examples of the name Isaias can be found in the Septuagint, the earliest surviving Greek translation of the Hebrew Bible, dating back to the 3rd century BCE. In this translation, the Hebrew name "Yshāyāhū" was rendered as "Ēsaias" in Greek.

Throughout history, several notable individuals have borne the name Isaias. One of the most famous was Isaias of Gaza (c. 450 - c. 518 CE), a Greek Neoplatonist philosopher and commentator on the works of Aristotle.

Another prominent figure was Isaias of Cyprus (c. 755 - 807 CE), a Byzantine monk and saint who is celebrated for his role in the restoration of icons during the Second Iconoclastic Controversy.

In the Middle Ages, Isaias of Trani (c. 1180 - c. 1250) was a renowned Italian rabbi and Talmudic scholar who made significant contributions to the study of Jewish law.

During the Renaissance, Isaias Thedingo (c. 1490 - c. 1550) was a German humanist and Hebraist who played a crucial role in the development of Hebrew studies in Europe.

In more recent times, Isaias Afwerki (born 1946) is the current President of Eritrea, having led the country since its independence in 1993.

The name Isaias has been used across various cultures and religions, reflecting its biblical origins and the influence of the prophet Isaiah. Its enduring popularity is a testament to the profound impact of this ancient figure on the naming traditions of many societies.