Regan

(male), (female) As a boy's name, this is a transferred use of the Irish surname Re(a)gan (Gaelic Ó Riagáin; see Reagan). The girl's name, however, may at least in part be from the name of one of the three daughters in Shakespeare's King Lear (1605), a most unattractive character, who flatters her father into giving her half his kingdom and then turns him out into a raging storm at night. It is not known where Shakespeare got the name; he presumably believed it to be of Celtic origin. It can be identified with the Irish Gaelic word ríogan ‘queen’ (pronounced ‘ree-gan’).