Isaak's Grandfather is an Unnamed Character in DEXTER. He is the grandfather of Isaak Sirko and had a brother that was a war hero that served in the Red Army during World War II. A teenager at the time, his brother returned home to be praised by those in Kiev, Ukraine until a Soviet Party Official became jealous and took away their home. His brother protested this action and was hung for it, something that affected Isaak's grandfather deeply...the lust for revenge strong in his eyes.

Uncomfortable with the boy, the party official sent him to imprisonment in Siberia where he spent much of his life just trying to survive however he always remained patiently waiting for the chance to gain revenge. This would finally come after the fall of the Soviet Union, allowing him to return to Kiev to celebrate with the others. Upon returning, he managed to find the official and keeping true to his long desired intent...shoved a six-inch knife into his kidney (thus ending his life).