In Irish mythology, Clíodhna (Clídna, Clionadh, Clíodna, Clíona, transliterated to Cleena in English) is a Queen of the Banshees of the Tuatha Dé Danann. Clíodna of Carrigcleena is the potent banshee that rules as queen over the sidheog (fairy women of the hills) of South Munster, or Desmond.

In some Irish myths, Clíodhna is a goddess of love and beauty, and the patron of County Cork. She is said to have three brightly coloured birds who eat apples from an otherworldly tree and whose sweet song heals the sick people. She leaves the otherworldly island of Tír Tairngire ("the land of promise") to be with her mortal lover, Ciabhán, but is taken by a wave as she sleeps due to the music played by a minstrel of Manannan mac Lir in Glandore harbour in County Cork: the tide there is known as Tonn Chlíodhna, "Clíodhna's Wave". Whether she drowns or not depends on the version being told, along with many other details of the story.

She had her palace in the heart of a pile of rocks, 5 mi (8.0 km) from Mallow, which is still commonly known by the name of Carrig-Cleena, and numerous legends about her are told above the Munster peasantry.

In general, it has been observed that Clíona is especially associated with old Irish families of Munster. Clíona has long been associated with the lands that had been the territory of the Ui-Fidgheinte (O'Donovans and O'Collins) during their period of influence (circa 373 A.D. to 977 A.D.), or were later associated with what had been the Ui-Fidghente territory (MacCarthys and FitzGeralds).

Clíona is referred to as an unwelcome pursuer in Edward Walsh's poem, O’Donovan’s Daughter. And, in an ode praising Donel O'Donovan upon his accession to the chiefship of Clancahill, Domhnall Ó Donnabháin III he is referred to as the "Dragon of Clíodhna".

Clíodhna is also associated with the MacCarthy dynasty of Desmond, who adopted her as their fairy woman, and the O'Keeffes and FitzGerald dynasty, with whom she has had amorous affairs Clíodhna appears in the name of one O'Leary in a medieval pedigree, as Conor Clíodhna or "Conor of Clíodhna", and it is notable that the family were originally based in the area of Rosscarbery, very near to Glandore, before moving north to Muskerry. The O'Learys belong to the ancient Corcu Loígde.

Surviving traditions of Clíodhna in narrative and poetry associate her with the O'Keeffes and O'Donovans. The latter, originally from Uí Fidgenti in North Munster with its own traditions, where their original goddess was Mongfind, later moved south to Carbery on Cuan Dor Harbour, Clíodhna's traditional abode on the South Munster coast, and she then features in poetry associated with them. The O'Keeffe narrative tradition is more extensive, and Clíodhna has other Desmond associations too.

Clíodhna is said to be a rival of Aibell, in one tale, Clíodhna cast a spell that turned Aibell into a white cat.

The most traditional story of the famous Blarney Stone involves Clíodhna. Cormac Laidir MacCarthy, the builder of Blarney Castle, being involved in a lawsuit, appealed to Clíodhna for her assistance. She told him to kiss the first stone he found in the morning on his way to court, and he did so, with the result that he pleaded his case with great eloquence and won. Thus the Blarney Stone is said to impart "the ability to deceive without offending". He then incorporated it into the parapet of the castle. To be fair, Clíodhna does not take credit for all the blarney of the MacCarthys. Queen Elizabeth noted in frustration that she could not effect a negotiation with Cormac MacCarthy, whose seat was Blarney Castle, as everything he said was 'Blarney, as what he says he does not mean'.