Question: Who is the paternal grandfather of Alexios Komnenos (Son Of Andronikos I)?
Answer: Isaac Komnenos

Andronikos I Komnenos (– 12 September 1185), usually Latinized as Andronicus I Comnenus, was Byzantine Emperor from 1183 to 1185. He was the son of Isaac Komnenos and the grandson of the emperor Alexios I.