Goll is a one-eyed, aged warrior who lives in the village that Bec grew up in. Goll is like a father figure to Bec. He was the one who found the little girl as an infant and brought her into the rath. At one point, Goll was king of the MacConn, but he gave up the position when he got older. Goll went with Bec and Drust on the quest to destroy the lodestone that was allowing the Demonata to cross into the human world. During the course of this journey, he died in the final battle at the entrance of the tunnel.
Likely a reference to Irish/Scottish legend's "Goll mac Morna" a Knight of Fianna who also lost an eye in battle.
"Bec" - Book 4