Yu Di (于頔; died 818), courtesy name Yunyuan (允元), formally initially Duke Li of Yan (燕厲公) and later Duke Si of Yan (燕思公), was a Chinese diplomat, military general, politician, and warlord during the Tang dynasty. He was a powerful warlord at the end of the reign of Emperor Dezong but submitted to imperial authority during the reign of Emperor Dezong's grandson Emperor Xianzong.