Phantasm is a reinvention of an older Batman villain called The Reaper. Let's take a look:
Fictional character biographies
Dr. Benjamin Gruener
Dr. Benjamin Gruener is a German Jew who was placed in a concentration camp run by Colonel Kurt Schloss. He kills Schloss at a Halloween parade and seemingly dies battling Batman when he falls off the edge of a dam. In Tony S. Daniel's "Batman: Life After Death" story arc, Hugo Strange resurrects Gruener and manipulates him into becoming a mass murderer. However, Batman makes Gruener see that Strange is using him before leaving.
Judson Caspian
Judson Caspian is a socialite by day and a vigilante by night. After losing his wife to a robber in the streets, he becomes the Reaper, targeting public menaces and murdering them with a scythe. He has a run-in with Green Lantern Alan Scott before traveling to Europe and disappearing. Several decades later, Caspian reassumes the Reaper identity and battles Batman. Batman works with the mob and Joe Chill to battle the Reaper, who eventually kills Chill. Caspian is later killed in a battle with Batman after choosing to fall off a ledge.
Joe Chill Jr.
In the 1991 one-shot sequel Batman: Full Circle, Chill's son Joe Jr. briefly assumes the mantle of Reaper as part of a plan to drive Batman insane. He eventually unmasks Batman, but does not recognize him. Chill attempts to mentally break Batman, who escapes and spares him.