As all men of House Havilliard, Gavin was tall and lean with dark hair.
During the war with the Valg King, Erawan, he fell in love with Elena Galathynius, princess of Terrasen. Together, they defeated Erawan in the depths of the Ruhnn Mountains. Eventually they got married, and Brannon Galathynius, Elena's father, gifted Gavin with a large territory - the future kingdom of Adarlan. He is buried beneath the old castle of Rifthold with his wife.
- 'Gavin' is a Scottish form of old Celtic 'Gobannonos', meaning blacksmith.
- He is mentioned by Elena Galathynius in Throne of Glass, as the previous owner of Damaris and Elena's husband, the first king of Adarlan.
- He does not think much about Hollin Havilliard, Dorian Havilliard's younger brother.
- He views Adarlan as his greatest achievement, his pride and joy.