In Greek mythology, Alseids were the nymphs of glens and groves. They liked to scare travelers. Of the Classical writers, the first and perhaps only poet to use the term alseid is Homer. Rather than alseid he used alsea. The three uses of alsea by Homer are as follows:
"The nymphs who live in the lovely groves (alsea), and the springs of rivers (pegai potamon) and the grassy meadows (pisea poiêenta)."
"They [nymphs] come from springs (krênai), they come from groves (alsea), they come from the sacred rivers (potamoi) flowing seawards."
"The nymphs [of Mount Ida] who haunt the pleasant woods (alsea), or of those who inhabit this lovely mountain (oros) and the springs of rivers (pegai potamoi) and grassy meads (pisea)."