origins
German origin
Cagle is the anglicization of the German surname Kegel (see Leonhart Cagle).
Irish origin
The original Cagle surname is an ancient Mayo family tracing its ancestry of Irish origin before the year 1100 and appears first in the ancient records in Mayo.
alleged French origin
(The French origin cited at http://www.archives.com/genealogy/family-history-cagle.html appears to be spurious.)