Kenneth I and II

There was even a Kenneth III!

According to tradition, the Scottish nation was founded in 843 by Cináed mac Ailpín (Kenneth MacAlpin – literally, the son of Alpin). Kenneth was a Gael, who is thought to have become King of the Picts by matrilineal descent (as was the custom). (The Picts had inhabited northern and eastern Scotland since Roman times; the Gaels spread into Scotland from Ireland some time around the 5th century AD.)

Kenneth was succeeded by his brother Donald I, who in turn was succeeded by his son Giric. All subsequent kings (and sovereign queens) of Scotland were descended from Kenneth. Kenneth II, who ruled from 971 to 995, was his great–great–grandson; Kenneth III (997–1005) was his great–great–great–grandson (nephew of Kenneth II).

For comparison: England was ruled from 839 to 856 by Æthelwulf, the father of Alfred the Great. Alfred ruled from 871 to 899 (following three of his elder brothers in turn). England was ruled from 978 to 1016 by Æthelred the Unready.