Saint Canna was a 6th century mother of saints and eventual nun in south Wales.

Canna was supposedly a Breton princess, the daughter of King Tudur Mawr, nephew of King Arthur. She came to Wales with her husband, Saint Sadurn, and their son, Saint Crallo. Sadurn left her, however, to become a hermit on Anglesey and she remarried and became the mother of Saint Elian Geimiad. However, these details of her early life are known only from the writings of the unreliable Iolo Morganwg. In later life, she certainly seems to have become a nun and lived at Llangan, Pembrokeshire. She also founded churches at Llangan, Glamorgan where she was deemed important enough to have her image carved into the church cross. The nearby Ffynnon Ganna, Canna's Holy Well, was a site for pilgrimage for many centuries after her death. Her name also appears as part of two Cardiff suburbs: Canton (English translation of the Welsh Treganna, 'Saint Canna's Town'); and Pontcanna (Welsh for 'Canna's Bridge'). Canna's Feast day is celebrated on the 25 October.

A Masonic Lodge No.6725, within South Wales Eastern Division, is named after Saint Canna.