Thailand's King Bhumibol Adulyadej died aged 88, according to a statement from the Royal Palace read on state TV Thursday.
The announcement followed a days-long outpouring of support since the king was hospitalized. He underwent medical procedures over the weekend.
King Bhumibol ascended to the throne 70 years ago, making him the world's longest-reigning living monarch, before his death.
Thais had flocked to the hospital in which he was being held, dressed predominantly in pink -- an auspicious color believed to restore health -- and yellow, which is the color of the King.