Chin Peng, who led a bloody uprising against British rule in Malaysia then lived in exile for five decades has died in a Bangkok hospital, Thai officials said.
A Thai army official said Chin Peng, who was reportedly 88 or 90, died of cancer.
He was Malaysia's best-known former communist guerrilla who led an uprising against British and Commonwealth forces during the period known as the Emergency, the bloodiest time in the country's modern history. Around 10,000 people are believed to have been killed.
Chin Peng lost a legal struggle in recent years to be allowed back into Malaysia. Government leaders insisted his return would upset many Malaysians who lost their loved ones during the communist insurgency.