The name Alexus is a modern variation of the ancient Greek name Alexios or Alexis, which is derived from the Greek word "alexo" meaning "to defend" or "to help". This name originates from the Greek language and culture, and its earliest recorded use dates back to the 4th century BCE.

The name Alexios or Alexis was particularly popular among Byzantine emperors and noble families during the Middle Ages. One of the most notable historical figures with this name was Alexios I Komnenos, a Byzantine emperor who ruled from 1081 to 1118 CE. He played a crucial role in the Byzantine empire's struggle against the Seljuk Turks and the First Crusade.

Another famous bearer of the name Alexios was Saint Alexios, a 5th-century Syrian saint who is venerated in the Eastern Orthodox and Catholic churches. According to legend, he lived as a beggar in his father's house for many years, unrecognized by his family, to pursue a life of humility and piety.

In the realm of literature, the name Alexis appears in the works of ancient Greek poets and playwrights, such as in Virgil's pastoral poem "Eclogues" and in the comedies of Plautus.

The variation "Alexus" emerged in more recent times, likely as a modern adaptation of the traditional Greek name. One notable figure with this spelling was Alexus Trubetskov, a Russian nobleman and military officer who lived in the 18th century and played a role in the Russian Empire's expansion into Siberia.

Another historical figure with the name Alexus was Alexus Charpentier, a French composer and music theorist who lived in the 17th century and made significant contributions to the development of French baroque music.

While the name Alexus is relatively uncommon compared to its traditional Greek counterparts, it has been used throughout history, though often as a variant spelling or modernization of the ancient name Alexios or Alexis.