Ildulb mac Causantín, anglicised as Indulf or Indulph,[1] nicknamed An Ionsaighthigh, "the Aggressor"[2] (died 962) was king of Alba from 954 to 962.

He was the son of Constantine II; his mother may have been a daughter of Earl Eadulf I of Bernicia, who was an exile in Scotland.

[5] The Chronicle of the Kings of Alba says: "In his time oppidum Eden", usually identified as Edinburgh,[6] "was evacuated, and abandoned to the Scots until the present day."

However, the conquest of Lothian is likely to have been a process rather than a single event, and the frontier between the lands of the kings of Alba and Bernicia may have lain south and east of Edinburgh many years before Indulf's reign.

[7] Indulf's death is reported by the Chronicon Scotorum in 962, the Chronicle of the Kings of Alba adding that he was killed fighting Vikings near Cullen, at the Battle of Bauds.