Peter Helias (Latin: Petrus Helias or Helyas; c. 1100 – after 1166) was a medieval priest and philosopher. Born in Poitiers, he became a pupil of Thierry of Chartres at Paris in the 1130s, also teaching grammar and rhetoric in his school. Around 1155 he returned to Poitiers where he later died. Through Thierry, he is meant to have been influenced particularly by Boethius; other influences include William of Conches. He contributed to the theory of substance and influenced Roger Bacon's Overview of Grammar.