Thierry IV or Theoderic IV (ca. 720 – ca. 782) was a Frankish noble. Count of Autun and Toulouse; he was thought to be a son of Sigebert V, and grandson of Sigebert IV of Raze. It is now well documented that it was a hoax (see Priory of Sion). Thierry married Auda, daughter of Charles Martel, sister of Pepin III.