Igor "Iggy" Wiggum is the deceased father of Clancy Wiggum, Springfield's Chief of Police, father-in-law of Sarah Wiggum and grandfather of Ralph Wiggum. He was, from World War Two, one of the members of the Flying Hellfish.
During World War Two, he served in the United States Army in Europe alongside Abraham Simpson, C. Montgomery Burns, Milton Haas and Arnie Gumble. He has the same personality as his son Clancy, although he seems more well-versed in terms of military standards, as he states that they shouldn't steal things from civilians when the unit caught Private Burns trying to steal the paintings from the German Occupied Castle. His clumsy behavior (such as leaving a un-pinned grenade in his backpack) is similar to his son's however. He died in a parade float accident in 1979 with four other members.
Given the fact that he mentioned having a grenade that he un-pinned and exploded in his backpack, Iggy was presumably the unit's Grenadier.