Where does “Алексеев” come from?

Алексеев (Russian) comes from Russian Алексе́й, from Russian Алекси́й, from Ancient Greek Ἀλέξιος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Ancestry of “Алексеев”, step by step

Алексеев traces back through two separate lines of ancestry.

via Russian Алексе́й

StepLanguageWordMeaning
1RussianАлексе́йAlpha (A in the ICAO spelling alphabet)
2RussianАлекси́й
3Ancient GreekἈλέξιοςhelper, defender
4Ancient Greek-ῐοςbelonging to; of”, “belonging to”, “pertaining to
5Proto-Indo-European-yósCreates adjectives from noun or verb stems

via Russian ев

StepLanguageWordMeaning
1Russianевshort past adverbial imperfective participle of...

Words derived from “Алексеев

Every word from Proto-Indo-European -yósEvery word from Ancient Greek -ῐοςEvery word from Ancient Greek Ἀλέξιος