Ragnvald the Mountain-High was a petty king of Vestfold in what is today Norway. He was the son of Olaf Geirstad-Alf and the cousin of Harald Fairhair.

His greatest contribution to posterity was that he asked the skald Pjódólfr of Hvinir to compose a poem about his ancestry. This poem is known as Ynglingatal and is not only one of the oldest, but also one of the most famous and debated of the Old Norse poems.

Pjódólfr ended the poem with these lines:

Under the heaven's blue dome, a name
I never knew more true to fame
Than Rognvald bore; whose skilful hand
Could tame the scorners of the land, --
Rognvald, who knew so well to guide
The wild sea-horses through the tide:
The "Mountain-high" was the proud name
By which the king was known to fame.