Killy is a variant form of the English, German, and Latinized name Achilles.
Killy is also a variant form of the English, French, and Irish name Cillian in the English language.
Killy is seldom used as a baby name for boys. It is not in the top 1000 names. Within the group of boy names directly related to Killy, Achilles was the most frequently used in 2018.