Tristan is a Celtic name. There was a tale about a man named Tristan and he was a knight of the Round Table. He was in a tale called "Tristan and Isolde"about Tristan going to an island and falling in love with a woman named Isolde. Unfortunately, Isolde had to marry King Mark instead. In Welsh, it means "Clanking of Swords". The name is probably based off of the French meaning, "triste" which means sad. The name is very popular in Spain.