Achaius may refer to: * John Capellanus (died 1147), Bishop of Glasgow nicknamed "Achaius" * Achaius, one of the

legendary kings of Scotland The Scottish Renaissance humanist George Buchanan gave a long list of Scottish Kings in his history of Scotland—published in Latin as ''Rerum Scoticarum Historia'' in 1582—most of whom are now considered by historians to be figures of legend ...

* Achaius, a genus of wasp within the family Ichneumonidae

See also