Genghis Khan
No accurate portraits of Genghis Khan exist, and any surviving depictions of him are considered to be artistic interpretations.  Persian historian Rashid-al-Din recorded in his "Chronicles" that the legendary "glittering" ancestor of Genghis was tall, long-bearded, red-haired, and green-eyed.  Rashid al-Din also described the first meeting of Genghis and Kublai Khan, when Genghis was shocked to find that Kublai had not inherited his red hair.  Also according to al-Din, Genghis's Borjigid clan had a legend involving their origins: it began as the result of an affair between Alan-ko and a stranger to her land, a glittering man who happened to have red hair and bluish-green eyes.  Modern historian Paul Ratchnevsky has suggested in his Genghis biography that the "glittering man" may have been from the Kyrgyz people, who historically displayed these same characteristics.  Controversies aside, the closest depiction generally accepted by most historians is the portrait currently in the National Palace Museum in Taipei, Taiwan (see picture above).