Thailand's king Adulyadej was the richest monarch
Thailand's late King Bhumibol Adulyadej was the richest monarch with an estimated worth of $30 billion as of April 2011, according to Forbes. Known as King Bhumibol the Great, he was the ninth monarch of Thailand from the Chakri Dynasty as Rama IX. The 88-year-old Thai king, who was the world's longest reigning monarch, died on Thursday.