Regan f
English: apparently of Shakespearian origin. This is the name of one of the three daughters in 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. Modern use has been reinforced by the Irish surname Re(a)gan (Gaelic Ó Riagáin).
First names dictionary. 2012.