Thiota (; 847 AD) was a Christian woman and false prophetess of the ninth century convicted of heresy. She was originally from Alemannia (then part of East Francia), and in 847 she began prophesying that the world would end that year.
Her story is known from the Annales Fuldenses which record that she disturbed the diocese of Bishop Salomon, that is, the Diocese of Constance, before arriving in Mainz. A large number of people were persuaded by her words, as well as even some clerics. In fear, many gave her gifts and sought prayers.