Bender, 35, had been in critical condition after being shot in the head a week ago at the CCC, a nightclub on Eight Mile Road, the border between Detroit and the northern suburbs.
He died early Tuesday, said Wende Berry, a spokeswoman for St. John Hospital and Medical Center.
Detroit police have said they were told by witnesses that Proof shot Bender during a dispute at the after-hours club. Bender's cousin, Mario Etheridge, then shot and killed Proof, whose real name was Deshaun Holton, officers said.
Proof, 32, was a close friend of Eminem and had a small part in his 2002 movie, "8 Mile."
Etheridge, 28, is charged with carrying a concealed weapon and discharge of a firearm in a building. He has pleaded not guilty.
He posted $7,000 bond and was released from the Wayne County Jail on Sunday afternoon.
Meanwhile, a viewing for Proof, was to be held Tuesday. A funeral was scheduled for Wednesday.