The Ulaid or Ulaidh are a people of early Ireland who give their name to the modern province of Ulster.

The first part of the name Ulster comes from Ulaidh; the latter part of the name ("ster") comes either from the English possessive ending -s and Irish tír (Ulaidhs tír) or the Old Norse staðr, both of which mean "land" or "territory".In medieval texts they are also referred to as the Clanna Rudraige, meaning "descendants of Rudraige".

The Ulster Cycle of Irish mythology is called An Rúraíocht.