Taj al-Din Yildiz (also spelled Yaldiz, Yildoz, and Yalduz, Persian: تاجالدین ییلدز) was a Turkic slave commander of the Ghurids, who, after the death of Sultan Mu'izz al-Din Muhammad, became the ruler of Ghazni, while, however, still recognizing Ghurid authority.
After the death of Sultan Mu'izz al-Din Muhammad, two factions arose in the Ghurid Empire; a faction of Turkic ghulams, who supported Mu'izz's nephew Ghiyath al-Din Mahmud, while the other faction consisted of native Iranian soldiers, who supported the Ghurid ruler of Bamiyan, Baha al-Din Sam II. Baha al-Din Sam II, however, died after a few days later, which made the Iranian soldiers support his two sons Jalal al-Din Ali and Ala al-Din Muhammad. Ghiyath, however, managed to emerge victorious during the struggle, and became the ruler of Firuzkuh. Meanwhile, Yildiz seized Ghazni from the Ghurid rulers of Bamiyan, but shortly recognized the authority of Ghiyath.
Ghiyath, not glad about Tajuddin controlling Ghazni, and not daring to leave Ghur unprotected, requested help from the Khwarazmian Muhammad II. Muhammad, however, instead invaded the domains of Ghiyath, capturing Balkh and Tirmidh. In 1208, the semi-independent Ghurid governor of India, Qutb-ud-din Aibak, attacked and occupied Ghazni, but was defeated by Yildiz forty days later.
In 1214, Yildiz killed Ala al-Din Atsiz, and put the latter's cousin Ala al-Din Ali on the Ghurid throne as his puppet. However, one year later, Muhammad II conquered Firuzkuh and captured Ala al-Din Ali; he shortly marched to Ghazni, where he decisively defeated Yildiz, who fled to Punjab and captured Lahore from Nasir-ud-Din Qabacha. Yildiz later fought the Turkic ruler Iltutmish, and laid claim to the throne of Delhi as the heir to Mu'izz al-Din Muhammad. Iltutmish refused, stating