Mustafa Akarsu was killed Friday when a Marxist terrorist blew himself up at the embassy gate, the Anatolia News Agency reported Saturday.
U.S. Ambassador Francis Ricciardone and his wife visited Akarsu's family and later called the guard "a great hero."
Speaking to reporters, the ambassador said, "God knows how many would have died if he hadn't been there,"
A journalist visiting the embassy was wounded, and two other guards at the checkpoint survived, CNN reported.
The embassy is located in a central part of the city that is considered very secure. Regardless, security measures around the embassy have been tightened. Residents of the Istanbul neighborhood are escorted to and from their homes by police and ambulances have been posted in the area.
Istanbul police have identified the bomber as Ecevit Shanli, a member of the Revolutionary People's Liberation Party (DHKP-C), a Marxist-Leninist organization.
While Shanli was known to both U.S. and Turkish intelligence agencies, they have not revealed why he targeted the embassy.
Since the first of the year, 85 members of the group have been arrested, said Hasan Selim Ozertem, a security expert at the International Strategic Research Organization in Ankara.