Ulaid (Old Irish, pronounced [ˈuləðʲ]) or Ulaidh (Modern Irish, pronounced [ˈʊlˠiː, ˈʊlˠə]) was a Gaelic over-kingdom in north-eastern Ireland during the Middle Ages made up of a confederation of dynastic groups. Alternative names include Ulidia, which is the Latin form of Ulaid, and in Cóiced, Irish for 'the Fifth'. The king of Ulaid was called the rí Ulad or rí in Chóicid.
Ulaid also refers to a people of early Ireland, and it is from them that the province of Ulster derives its name. Some of the dynasties in the over-kingdom claimed descent from the Ulaid, but others are cited as being of Cruithin descent. In historical documents, the term Ulaid was used to refer to the population group of which the Dál Fiatach was the ruling dynasty. As such, the title rí Ulad held two meanings: over-king of the Kingdom of Ulaid and king of the Ulaid people, as in the Dál Fiatach.