Keagan is a spelling of Keegan, an Irish surname from Mac Aodhagáin, "son of little Aodh", in which Aodh is the old Irish word for "fire" and the name of a Celtic sun god. The surname turned first name in America in the 1980s together with Reagan and Teagan. Keagan sat in the US top 1000 from 2000 to about 2019 with a peak of number 489 in 2008 and has fallen to number 1614 in 2025.