Killian is the anglicized spelling of the Irish Cillian, usually explained as "little church" from ceall, or as "strife". Saint Kilian, an Irish missionary bishop, is the patron saint of Würzburg in Germany, and actor Cillian Murphy has spread the original spelling. Killian entered the US top 1000 in 2007, peaked at number 248 in 2017 and holds number 418 in 2025.