Halley Astry, born in 1824, is a homeroom professor at the Alzano Imperial Magic Academy. He achieved the Quinde (Rank 5) mage rank before joining the faculty. Records confirm his tenure began by 1852, when he was 29, though his earlier career path is less clear.

As a faculty member, Halley exhibits consistent antagonism toward fellow instructor Glenn Radars. He criticizes Glenn's lack of teaching credentials and perceived incompetence, driven by a strong adherence to institutional standards and concern for the academy's reputation. Despite this harsh demeanor, Halley demonstrates underlying dedication to the institution, notably participating in its defense during the "Fejite's Worst Three Days" crisis, revealing a commitment extending beyond mere professionalism.

Portrayals vary across adaptations. The light novel and manga show Halley expressing disappointment when a sacrificial student loses early in the Spirit Defence competition, hoping for better performance. The anime intensifies his negativity, depicting him fully expecting the student's immediate defeat. This difference highlights his role as a narrative foil while preserving core traits.

Halley maintains a competitive relationship with colleague Celica Arfonia, establishing them as professional rivals within the academy hierarchy. His interactions with students follow traditional teaching methods, contrasting sharply with Glenn's unconventional style. Halley's confrontations with Glenn specifically target Glenn's third-rate mage status and lack of credentials, upholding academic conventions through motivations blending institutional concern with personal disdain.

Beyond academics, Halley participates in events including the Magic Competition and Invasion of Fejite arcs. Specific developmental milestones during these events remain incompletely documented in available records. His character maintains a consistent presence across media, with official descriptions noting ongoing investigation into his background.