Hopi katsina dolls are wooden effigies of the katsinam (plural), or benevolent spirit beings, who visit the Hopi for about half of every year. Traditionally carved from cottonwood root by Hopi men, they are tangible evidence of the katsinam's power and wisdom.

According to Hopi tradition, the katsinam once visited in person, but now come as clouds down from the mountains or up from the earth. They begin arriving in late December, at the winter solstice. Masked and costumed Hopi men assume their powers and prestige in ceremonies and dances held until the katsinam depart in July. Though only men can be katsinam, women and children play important roles as their audience; all Hopi men and women belong to the Katsina Society.

The Hopi recognize several hundred katsinam. Some originated at other pueblos. Many came from Zuni without their original legends and other religious connotations, and have since come to look much more like Hopi katsinam.

Hopi katsinam can be male or female, and represent plants, animals, insects, human qualities, the creative force of the sun, and even death. Some are demons who frighten children into behaving properly; most are clan ancestors and beneficent beings. They are messengers who accept Hopi gifts and prayers for health, fertility, and rain and carry them back to the gods. Their role as rainmakers is particularly important to the Hopi, whose agriculture in the high, arid desert of northeastern Arizona has always been precarious.

Three main ceremonies are performed by and for the katsinam during their stay in the villages: Soyalangwu, a winter solstice ceremony in December; Powamuya in February, when the katsinam are asked to appear; and Niman, the home-going ceremony, after the summer solstice. Between Powamuya and Niman, they perform several dances that help bring rain, promote the growth of crops, and increase the number of animals the Hopi depend on for survival. Early in the year they are held in underground ceremonial chambers called kivas. As spring arrives, the dances move out onto the plazas, where they last from morning until dusk. At the end of Niman, the katsinam return to the spirit world.

During the dances and ceremonies, katsina dolls, or tithu (singular: tihu), are given by the katsinam to infants of both sexes, young girls, and women. Most are given out during Powamuya and Niman. Girls at or near marriageable age receive most of them, although married women sometimes get them from their husbands. A woman who receives a tihu treats it with great respect, hanging it from a beam or wall in her house where it won't come to harm and can continue to benefit her and her family.

Whereas traditionally Hopi katsina dolls were carved by the katsinam in the kivas and were used entirely within Hopi culture, since the late 1800s many dolls have been carved as art objects and sold to the general public. Market demand has increased Hopi production of the dolls while adding new technical skills and styles to the Hopi carvers' repertoires.

Katsina dolls are most easily identified by their colors, the types and arrangements of feathers they wear, and the tools, weapons, and other accessories they hold or carry on their backs, all of which are symbols laden with religious meaning.