Aleister is a Scottish form of Alexander, ultimately from Greek, meaning defender of men.
Aleister is a Scottish Gaelic transliteration of Alexander, the great Macedonian name derived from the Greek Alexandros — a compound of alexein ("to defend") and aner/andros ("man"), yielding the enduring meaning "defender of men." In the Gaelic-speaking Highlands and islands of Scotland, Alexander was commonly rendered as Alasdair, Alister, or Aleister, reflecting the phonological patterns of a language that had been transforming Greek and Latin names through its own sonic register for over a thousand years.
The variant spelling with the distinctive -ei- diphthong is relatively rare, lending it an archaic, almost rune-carved quality. The name's modern associations are almost entirely dominated by one figure: Edward Alexander Crowley (1875–1947), who adopted the name Aleister as a young man and became, under it, the century's most notorious occultist, mystic, and provocateur. Self-styled "the Great Beast" and "the wickedest man in the world," Crowley founded the philosophical and magical system of Thelema, authored dozens of esoteric texts, and scandalized Edwardian society with deliberate extravagance.
His shadow falls long across the name — it has been borne by musicians, artists, and fictional villains as an homage to that transgressive legacy, and it sits comfortably in the gothic, neopagan, and counterculture naming traditions. Yet stripped of that association, it is simply a beautiful, resonant Scottish name: strong consonants, elegant spelling, and a lineage that connects directly to one of history's greatest conquerors.