Niall mac Cailein (Neil Campbell)

Sir Niall mac Cailein, also called Neil or Nigel Campbell (d. 1316), was a son of Cailean Mór and a lifelong warrior in the service of Robert the Bruce. One of Bruce's earliest adherents in 1306, he stood by him after the defeats at Methven and Dalrigh and fought the English and the MacDougalls.

He negotiated with the English crown in 1309 and 1314, and married the king's sister Mary Bruce. His service to the king elevated the Campbells in the Scottish nobility.