Alena 1

Allegedly also an archaic English diminutive of Magdalen: https://www.familysearch.org/wiki/en/England_Female_Nicknames_(National_Institute)

Also Sorbian: https://hsb.wiktionary.org/wiki/P%C5%99idawk:Lis%C4%87ina_zapados%C5%82owjanskich_p%C5%99edmjenow
https://hsb.wiktionary.org/wiki/P%C5%99idawk:Lis%C4%87ina_hornjoserbskich_p%C5%99edmjenow

This name is more common in Europe but it is getting more popular in the US.

Also Croatian.

Alena is very popular name in Czech Republic and Slovakia (Central Europe). [noted -ed]

Alena is very popular name in Belarus (Eastern Europe), it originated from the Greek name Helen.