Aitíth mac Laigni (died 898) (also Aidíth) was a King of Ulaid, which is now Ulster, Ireland. He belonged to a branch of the Dal nAraide known as the Uí Echach Cobo in the west part of county Down. He ruled as King of Ulaid from 896-98. His last direct ancestor to hold the throne of Ulaid was Fergus mac Áedáin (died 692) of whom he was a 6th generation descendant. He possibly became King of Coba (Cuib) in 882 on the death of Conallán mac Máele Dúin. His descendants, the Ua hAiteidh, dominated the Uí Echach Cobo from the late 10th century until the early 12th century.