Aarni
Not a folklore creature — Aarni is a Finnish avant-garde metal band (1998–present) by Master Warjomaa. The name was likely chosen for its mythological resonance (cf. 'aarni' as treasure guardian in Ganander), but no such entity exists in Finnish mythology. Ganander's Mythologia Fennica mentions 'aarni' as a treasure-guarding spirit (haltija), but the band is the primary modern referent.