legendary knight

A legendary knight is a warrior of medieval chivalric tradition whose deeds have passed into myth, folklore, or romantic literature.

Knights of the Round Table like Lancelot and Gawain exemplify the type, as does the historical El Cid, whose real exploits became embroidered with legend.

The phrase can also describe any modern figure whose achievements in a field seem almost mythically impressive: He's a legendary knight of the courtroom.