Etymology
* As an Irish surname, calque of mac cuilinn (“holly”) (see McCullen) and sometimes McQuillan.
* As an English surname, variant of Holley.
* As a Czech and Slovak surname, variant of Holý, Holy.
* Also as a locational English surname, from Old English hol leah (“wood, clearing, meadow”), compare Hollywood.
* Also as an English surname, short form of Holiday.
* Also as an English surname, after the holly tree.
* As a feminine given name popularized by Truman Capote's Breakfast at Tiffany's (especially the 1961 film adaptation starring Audrey Hepburn).