Eysteinn Valdason (Old Norse: ; Modern Icelandic: ) was a 10th-century Icelandic skald. Three half-stanzas from a poem about Thor are all that survive of his work. Preserved in Snorri Sturluson's Skáldskaparmál <small>(4)</small> only, they deal with Thor's fishing expedition with the giant Hymir, where the god attempts to kill Jörmungandr.