User blog comment:Avatar226/S-Class Contest/@comment-24066070-20131214101630/@comment-24066070-20131214184814

NoNickNeeded came sooooo close, I'll accept his answer, since he was thinking along the right track.

The answer I meant is: most guilds are named after a mythological being.

Fairy, Pegasus, Cerberus, Mermaid, Sylph, Phoenix, Lamia and even Caithshelter is likely named after a Cat Sidhe.