Thomas the Rhymer:
aka Thomas Learmont, Thomas of Erceldoune, Thomas of Britain.

ca. 1220-1297, Scotland.

Poet and prophet, possible author of the Tristan of Thomas (usually published with the Gottfried von Strassburg version). This version of the Tristan and Iseult legend was first published in 1804 by Sir Walter Scott, from a manuscript dating to about 1300. From that manuscript, little is known of Thomas, other than that he is a poet, fluent in the Anglo-Norman dialect of French, who according to von Strassburg lived either in Britain or Brittany, the former being more likely.

He is best known from the ballad "Thomas the Rhymer" (see above), included by Scott in his collection Minstrelsy of the Scottish Border. His prophecies first appeared in the 15th century Romance and Prophecies of Thomas of Erceldoune.

It seems that, like Merlin, Thomas, though a historical person, was at some point confused with an earlier legend about a Tom who is abducted by the Queen of Elfland and made her lover. This Tom is the same as Tom O'Bedlam (a song, as well as Edgar's mad persona in King Lear) and Tam Lin of the famous ballad.