Eochocán mac Áedo (died 883) was a Dál Fiatach king of Ulaid, which is now Ulster, Ireland. He was the grandson of Eochaid mac Fiachnai (died 810), a previous king of Ulaid. He ruled from 882-883. His father Áed mac Eochada had died in 839. In 882 he succeeded his brother Ainbíth mac Áedo as leth-rí (half-king or co-ruler) of Ulaid jointly with his other brother, Airemón mac Áedo (died 886). However, the next year in 883, Eochocán was killed by his nephews, the sons of Ainbíth.