Fergus Mór mac Eirc (Scottish Gaelic: Fergus Mòr Mac Earca) is a legendary king of Dál Riata.

He is the son of Erc.

While his historicity may be debatable, his posthumous importance as the founder of Scotland in the national myth of Medieval and Renaissance Scotland is not in doubt.

Rulers of Scotland from Cináed mac Ailpín until the present time claim descent from Fergus Mór (Fergus the Great).