From the experts:
Egan's likeness to the word eager gives this Irish surname a ready-to-please, effervescent energy, and it would make an appropriate substitute for the overused Aidan.
This popular Irish surname originated in County Tipperary.
Egan O'Rahilly (born Aogan O Raithaille) was the outstanding poet of his age, specializing in the vision poem, or aisling, in which he told of prophesies that Ireland would triumph over her enemies. In folklore, this Egan is depicted as a wise trickster.