Old Man Pollidori (played by Lloyd Berry) was the father of Dr. Francis Pollidori and father-in-law of Elizabeth Pollidori. Old Man Pollidori took in and cared for The Great Mutato, who had been created by his son and his horrific genetic experimentation on humans. Pollidori did his best to keep The Great Mutato safe, but was unable to restrain him from intruding the homes of and impregnating Shaineh Berkowitz and his daughter-in-law. Mulder and Scully met Pollidori while pursuing the "monster," but were told to mind their own business. After the pregnancy of Elizabeth, Francis went to see his father and murdered him.
Pollidori's body was buried by The Great Mutato in his own barn. The Great Mutato was devastated by the loss, and described to the mob of townspeople how Pollidori - to whom he referred to as his father - attempted to learn his son's scientific arts to create a mate. However, his father failed, leaving The Great Mutato alone. Old Man Pollidori kept a photo album of him and his adopted son in activities and places almost any normal family could be seen in. (TXF: "The Post-Modern Prometheus")