Aleksej is a Slavic form of Alexios, from Greek, meaning defender or protector.
Aleksej is the South Slavic and Russian orthographic form of Alexei — itself a variant of the Greek name Alexios (Ἀλέξιος), derived from the verb "alexein" (ἀλέξειν), meaning to defend, protect, or ward off. The root is the same that gives us Alexander (defender of men) and Alexandra, making Aleksej part of one of the great name dynasties of the Western and Eastern worlds, a name that has crowned kings and inspired poets across three thousand years. In the Greek East, Alexios was the name of three Byzantine emperors, most notably Alexios I Komnenos, whose reign in the late eleventh century coincided with the First Crusade and reshaped the medieval world.
In the Russian Imperial tradition, Aleksej (Алексей) is inseparable from the Romanov dynasty. Alexei Mikhailovich, the seventeenth-century tsar known as "the Quietest," was one of Russia's most important reforming monarchs, and Tsarevich Alexei Nikolaevich — the hemophiliac son of Nicholas II whose illness shadowed the final years of Imperial Russia — gave the name a tragic, romantic resonance that Tolstoy and countless historians have returned to. In literature, Alexei appears throughout Dostoevsky's work, most luminously as Alyosha Karamazov, the gentle, spiritual heart of "The Brothers Karamazov."
The specifically Slavic spelling Aleksej, with its characteristic "j" in place of the more Anglicized "i" or "y," signals a deliberate connection to Serbian, Slovenian, or Croatian linguistic tradition. It is a spelling that roots the bearer in a specific cultural geography — the South Slavic world — while the name itself resonates across the entire breadth of European history.