La Calavera Catrina is a Mexican cultural icon and popular figure appearing during the Day of the Dead in all countries that celebrate that holiday. She is a skeleton dressed in fine clothing, and is often decorated in the manner of a celebrative calavera.
Catrina was originally created by the Mexican artist José Guadalupe Posada c. 1910 as a satirical critique of Mexicans who were acting too European. She wears a fancy French hat, and her bone-white face was a commentary on women lightening their skin with makeup. The image headed a leaflet making an argument against European fashions, and taking pride in one's South American heritage.
The original image presented her as bare-shouldered, with an inelegant gaping grin (as is often the case with skulls). The popular image has her in proper (European) finery, in either French or Spanish derived dresses and frills. This change, and her first inklings of true popularity, came in 1947, when Diego Rivera completed his mural Sueño de una Tarde Dominical en la Alameda Central, which featured her prominently, this time dressed as a flapper, but with an impressive boa made from a feathered serpent.
Since the 40s, she has become less European, often presenting with long, dark hair, wearing dresses with in traditional cuts and patterns, and representing a more traditional view of death -- not as a death of a culture, but of a culture that accepts death as part of life. She is now a fixture of Día de Muertos, and is often associated with Santa Muerte (AKA Lady of the Dead), the Aztec goddess Mictecacihuatl, and calaveras mirroring elements taken from traditional skull carvings.