Zhang Jun (died January 20, 904), courtesy name Yuchuan, is an official of the Chinese dynasty Tang Dynasty, serving as a chancellor during the reigns of Emperor Xizong and Emperor Xizong's brother Emperor Zhaozong.

Early in Emperor Zhaozong's reign, Zhang is a major advocate for the imperial campaign to regain power from the regional warlords, but is removed after commanding a disastrous campaign against Li Keyong and forced into retirement.

Late in Emperor Zhaozong's reign, with Emperor Zhaozong physically controlled by another warlord, Zhu Quanzhong, who has designs on taking over the throne as emperor (and eventually does, founding Later Liang Dynasty), Zhu, while formerly an ally of Zhang's, is concerned that Zhang would encourage other warlords into a coordinated campaign against Zhu to stop his takeover, and so has his ally Zhang Quanyi slaughter Zhang Jun and his household.