Killelea is an Irish surname found originally in County Galway, documented from Elizabethan times at least. The current spelling is an Anglicization of an older Irish Gaelic form, probably Mac Giolla Leigh or Mac Giolla Leith. Variant spellings include Killilea, Killalea, Killela, Kilalea and Kellelea.
There are approximately 1000 Killeleas in the United States and a similar number in Australia, with smaller numbers in Ireland, England, and South Africa. The Australian Killeleas are mostly the descendants of Edward Killelea the convict, one of the "Kiltormer Four" who murdered two brothers in western Ireland in the mid-19th century.
There is an Australian state park named for Edward Killelea.