Theano was a philosopher from the Greek colony of Croton in southern Italy during the 6th century BCE. She is a central figure in the early Pythagorean school, a community focused on mathematics, asceticism, and a structured way of life. Her exact relationship to the founder, Pythagoras, is uncertain. Ancient sources traditionally identify her as his wife, though some suggest she may have been his daughter or a disciple. According to later accounts, she had children, including a daughter named Damo. Her presence highlights the notable inclusion of women in early Pythagorean philosophical practice.

No writings survive that can be reliably attributed to her. Later biographical sources, like the 10th-century Byzantine encyclopedia known as the Suda, list several works under her name, such as "On Piety," "Advice to Women," and "On Virtue." Modern scholars, however, consider these works to be spurious. They were likely composed centuries later as part of a tradition of pseudepigrapha—texts forged in the names of authoritative early figures to disseminate Pythagorean ideas.

Theano’s significance lies primarily in her symbolic role. The historical person is elusive, but the literary figure of Theano became an important vehicle for ethical teachings. In later antiquity, letters and treatises written in her name were used to present Pythagorean views on morality, piety, and the proper roles of women within the household. Thus, she represents both the participation of women in early philosophy and the later tradition of using legendary figures to transmit philosophical ideas.