Gary Holden is the father of Trevor Holden and husband of Patricia Holden.
He is shown to have a short temper and frequently lashes out at his son and wife. He is controlling of his wife's behavior which she tolerates stating that it is easier than arguing. Gary thinks little of his son's behavior for which the view has little context. He at one point strikes Trevor across the face when he suspects that Trevor has stolen his mother's medication. (S1E07: Protocol 5)
After the death of his mother, Gary embarks on a trip to her funeral though his son doesn't join him. Gary instead texts him to let him know he's en route. Meanwhile, Trevor is jogging with Philip Pearson when he receives the message; Philip mentions he has no knowledge of his grandma's passing as she was irrelevant to the Grand Plan, although he does claim that Trevor's late grandfather was considered a host candidate but never chosen. (S3E05: Naomi)