Killian graduated from University College Dublin in 2017 and started working for FarmGate Veterinary Group soon after. He is from Golden in County Tipperary but lived in Waterford for the first 9 years of his life. Killian grew up on a suckler beef and dairy goat farm. He is still actively involved in the running of the operation at home. He also breeds pedigree Simmental and Charolais cattle and attends many of the summer shows. Kilian is interested in bovine lameness, fertility and embryo transfer. In his spare time, he enjoys watching most sports especially rugby, hurling, Gaelic football, and horse racing.