Ildulb mac Causantín, anglicised as Indulf, nicknamed An Ionsaighthigh, "the Aggressor" (died 962) was king of Scots from 954. He was the son of Constantine II (Causantín mac Áeda); his mother may have been a daughter of Earl Eadulf I of Bernicia, who was an exile in Scotland.
John of Fordun and others supposed that Indulf had been king of Strathclyde in the reign of his predecessor, based on their understanding that the kingdom of Strathclyde had become a part of the kingdom of Alba in the 940s. This, however, is no longer accepted.
The Chronicle of the Kings of Alba says: "In his time oppidum Eden", usually identified as Edinburgh, "was evacuated, and abandoned to the Scots until the present day." This has been read as indicating that Lothian or some large part of it, fell to Indulf at this time. 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.
Indulf (Greek: Ἰνδούλφ), also known as Gundulf (Greek: Γουνδούλφ), was a Byzantine mercenary who defected to the Ostrogoths and became a leader in their army in the last years of the Gothic War of 535–554.
Indulf is first mentioned, by the historian Procopius, as a barbarian (in all probability a Goth) bodyguard of the Byzantine general Belisarius. When Belisarius departed Italy in early 549, Indulf remained behind, and soon after joined the Goths. In late spring/early summer of 549, the Ostrogoth king Totila (r. 541–552) entrusted him with a large army and a fleet, and sent him to campaign in Dalmatia, which the Byzantines had taken in 535/536. There, he used his known association with Belisarius to capture the fortified towns of Movicurum and Laureate, whose inhabitants had not learned of his volte-face. Indulf killed the inhabitants and plundered the two settlements and the surrounding countryside. He also defeated a Byzantine force sent against him by the local Byzantine governor and captured a number of supply ships destined for the Byzantine army in Italy, before returning with his men to Italy.