Abdelbaset al-Sarout, the 27-year-old footballer, was named the 'revolution goalkeeper, and singer', has also participated in an award-winning documentary.
Al-Sarout was wounded in clashes with regime forces in the northern Hama countryside in the early hours of Friday while fighting with rebels.
"He died of his wounds on Saturday," the head of the Britain-based Observatory, Rami Abdurrahman, said.
On the other hand, thousands of people have gathered to mourn al-Sarout on Sunday, who became an icon of the revolt against President Bashar Assad.