Killoren

Killoren was the husband of Vivian and a fallen hero of Lordaeron. He is the father of Thassarian and Leryssa. It was his spirit that Thassarian saw at Light's Hope Chapel, and helped to free him from the Lich King's control. Originally he was buried in Lordaeron but was moved to Light's Hope Chapel.

Speculation
Judging by Thassarian's age and his mother's sadness about her son following his footsteps, it is believed that he was killed during the Second War.