A Syrian revolution icon and footballer succumbed to his wounds at a Turkish hospital on Saturday, according to the Syrian Observatory for Human Rights.
Abdelbaset Sarout was wounded in clashes in Syria's northern Hama countryside and transported to Turkey for treatment, the rights group said.
"He died of his wounds on Saturday," said Rami Abdurrahman, head of the U.K.-based Observatory.
Sarout, 27, represented Syria at the U-17 and U-20 level as a goalkeeper and became a rebel commander when his hometown Homs came under regime attack from 2011 to 2014.
He was featured in the 2013 documentary The Return to Homs that won international awards.
Sarout, for many, was also the singer of the revolution.
In Youtube videos, he sang songs of independence and martyrdom.
"Oh father, our homeland is bleeding, our soil saddened,
Oh father, the children cry but who will answer their call,
Oh father, martyrdom is my dream, my dream for years..." he was seen singing in a 2016 video.
Turkey and Russia agreed last September to turn Idlib into a de-escalation zone in which acts of aggression would be expressly prohibited.
The Syrian regime, however, has consistently broken the terms of the truce, launching frequent attacks inside the de-escalation zone.
Syria has only just begun to emerge from a devastating conflict that began in 2011 when the Assad regime cracked down on demonstrators with unexpected severity.