one of five poets renowned among the Welsh in the latter part of the 6th century, according to the Historia Brittonum (c. 830).

The Book of Taliesin, the oldest surviving copy of his works (written about 700 years after his time), attributes to him a variety of poems, some on religious themes, some arcane verses that belong to Celtic mythological traditions and that are very difficult to decipher, and some that refer to known historical figures. Of this latter group, 12 have been identified as being the work of the 6th-century poet. Among these are poems praising Urien, king of the ancient Welsh territory of Rheged (the modern shires of Wigtown and Kirkcudbright in south Scotland), and lamenting the loss of Owain, son of Urien. A eulogy to Cynan Garwyn ap Brochfael, king of Powys, attributed to Taliesin, suggests that the poet may have been a native of Powys, Wales. The mythical visionary poet described in the folktale known as "Hanes Taliesin" (“The Story of Taliesin”) is a separate figure and a later medieval creation.