Sturla Þórðarson (1214–1284) was an Icelandic politician/chieftain and writer of sagas and contemporary history during the 13th century.
Sturla was the son of Þórður Sturluson and his mistress Þóra, and grandson of Sturla Þórðarson the elder. He was a nephew and pupil of the famous saga-writer Snorri Sturluson. He fought alongside Þórður kakali Sighvatsson during the Age of the Sturlungs.
He is best known for writing Íslendinga saga, the longest saga within Sturlunga saga, and Hákonar saga Hákonarsonar, the story of Haakon IV of Norway. He also wrote a saga of Haakon's son, Magnus the lawmender (Magnúss saga lagabœtis), of which only fragments have survived. Some scholars also believe him to have written Kristni saga and Sturlubók, a transcript of Landnáma. He is moreover listed in Skáldatal as the court skald of the Swedish ruler Birger Jarl.
Sturla was appointed law speaker over all of Iceland for a brief period after the dissolution of the Icelandic Commonwealth, and wrote the law book Járnsíða.
His brother was Ólafur Þórðarson hvítaskáld.