Clan Campbell (Gälisch: Clann Chaimbeul) ist ein großer und einflussreicher schottischer Clan. Sein Ursprung liegt vermutlich bei den Briten des Königreichs Strathclyde, deren originärer Sitz entweder Innis Chonnel Castle auf der Innis Chonnell im Loch Awe oder Caisteal na Nigheann Ruaidhe bei Loch Avich war.
In traditional genealogies of the Clan Campbell, its origins are placed amongst the ancient Britons of Strathclyde. However the earliest Campbell in written records is Gillespie who is recorded in 1263. Early grants to Gillespie and his relations were almost all in east-central Scotland. However the family's connection with Argyll came some generations before when a Campbell married the heiress of the O'Duines and she brought with her the Lordship of Loch Awe. Because of this the early clan name was Clan O'Duine and this was later supplanted by the style Clan Diarmid. This name came from a fancied connection to Diarmid the Boar, a great hero from early Celtic mythology. The original seat of the Clan Campbell was either Innis Chonnell Castle on Loch Awe or Caisteal na Nigheann Ruaidh on Loch Avich. The clan's power soon spread throughout Argyll however at first the Campbells were under the domination of the Lords of Lorne, chiefs of Clan MacDougall.