Regan is a name with a complex and multifaceted history, derived from both literary and Gaelic origins. In the context of English and literary usage, Regan first appears in the chronicles of Geoffrey of Monmouth as the name of a treacherous daughter of Leir. This figure was later adapted by William Shakespeare for his tragedy King Lear (1606), where Regan is one of Lear's two cruel and ungrateful elder daughters. Shakespeare's powerful portrayal cemented the name in literature as a symbol of treachery and manipulation. In the 20th century, the name gained a new and infamous association with the character Regan MacNeil from William Peter Blatty's novel The Exorcist (1971) and its film adaptation (1973). In this story, a young girl named Regan is possessed by a demon, adding a supernatural and disturbing layer to the name's connotations. Despite these dark associations, the name Regan has continued to be used in modern times, sometimes also as a variant of the name Reagan. Etymologically, Regan is derived from the Irish surname Ó Riagáin or Ó Ríogáin, meaning “descendant of Riagán,” which itself appears to be derived from the Gaelic word rí meaning “king” combined with a diminutive suffix, hence “little king” or “kingly.” Historically, the O'Regan family was a prominent clan in Ireland, with notable figures like Mathghamhain Ó Riagáin, king of Breagh, who in 1029 captured the king of Dublin. The name is also connected to the Reagan political surname, made famous by U.S. President Ronald Reagan, though the spelling differs slightly. Related variants include Raegan, Reagan, and Regana. While historically more common as a surname, Regan has settled into usage as a given name for girls, carrying both a literary mystique and a proud Irish heritage. Meaning: Little king; derived from Irish Ó RiagáinOrigin: Irish and EnglishType: Given name (female), also a surnameUsage regions: Ireland, English-speaking countries