Lucano the Great
Of all the giants in Arthurian romance, this one must rank as one of the least genetically plausible, in that his father was a lion and his mother a giantess.
Lucanor was an insane giant who ruled the fortress of Dianfer in the waste land of Lionferfo.
His brothers included Urgan the Hairy and the two giants of the Perilous Valley. Tristan slew Lucanor, all of his brothers, and his nephew Burletta.
Sources
Prose Tristan | 1230-1240
La Tavola Ritonda | 1325–1350