According to Kansas First News, family members confirmed that the Rev. Fred Phelps, Sr. passed away late Wednesday. He was 84 years old.
Phelps' church in Topeka, Kan. is known for anti-gay protests at military funerals.
The actions of the church sparked funeral protest laws all across the country and even made it all the way to the U.S. Supreme Court. In 2011, a free-speech ruling declared Westboro and its members couldn't be sued for monetary damages for inflicting pain on grieving families.
The church released a statement on its blog, but told ABC News there will be no further comment.