The bre'Unor name them the Children of b'Y'laggo and humans call them Changelings. The fir'Bolg, however, refuse to speak of them. -Changlings Description, Cast of Characters, Myth II: Chimera
Changlings were animated dead trees by the spirit of b'Y'laggo, an elemental spirit worshiped by the bre'Unor. They followed Gor-Ash and were major enemies to the fir'bolg. These creatures were only shown during Myth II: Chimera.