Phelps believed any misfortune, most infamously the deaths of American soldiers killed in Iraq and Afghanistan, was God's punishment for society's tolerance of homosexuality. He and his followers carried forward their message bluntly, holding held signs at funerals and public events that used ugly slurs and read "Thank God for dead soldiers." God, he preached, had nothing but anger and bile for the moral miscreants of his creation.
"Can you preach the Bible without preaching the hatred of God?" Phelps asked in a 2006 interview with The Associated Press. "The answer is absolutely not. And these preachers that muddle that and use that deliberately, ambiguously to prey on the follies and the fallacious notions of their people, that's a great sin."
For those who didn't like the message or the tactics, Phelps and his family had only disdain. "They need to drink a frosty mug of shut-the-hell-up and avert their eyes," his daughter, Shirley Phelps-Roper, once told a group of Kansas lawmakers.
The activities of Phelps' church, unaffiliated with any larger denomination, inspired a federal law and laws in more than 40 states limiting protests and picketing at funerals. He and a daughter were even barred from entering Britain for inciting hatred.
But in a major free-speech ruling in 2011, the U.S. Supreme Court held that the church and its members were protected by the U.S. Constitution's First Amendment and could not be sued for monetary damages for inflicting pain on grieving families.
Yet despite that legal victory, some gay rights advocates believe all the attention Phelps generated served to advance their cause.
Sue Hyde, a staff member at the National Gay and Lesbian Task Force, said plenty of churches and ministers preach a message that attacks gay people. But Phelps and his family had "taken this out on the streets," forcing people to confront their own views and rousing a protective instinct in parents and friends of gays and lesbians.
"It's actually a wonderful recruiting tool for a pro-equality, pro-social acceptance movement," she said. "To the Phelps family, that is not particularly important or relevant. They are not there to save us. They are there to advise us that we are doomed."
Once seen as the church's unchallengeable patriarch, Phelps' public visibility waned as he grew older and he became less active in the church's pickets, with daughters Shirley Phelps-Roper and Margie Phelps — an attorney who argued the church's case before the U.S. Supreme Court — most often speaking for Westboro. In the fall of 2013, even they were replaced by a church member not related to Phelps by blood as Westboro's chief spokesman.
In Phelps' later years, the protests themselves were largely ignored or led to counter demonstrations that easily shouted down Westboro's message. A motorcycle group known as the Patriot Guard arose to shield mourners at military funerals from Westboro's notorious signs. At the University of Missouri in 2014, hundreds of students gathered to surround the handful of church members who traveled to the campus after football player Michael Sam came out as gay.
Phelps' final weeks were shrouded in mystery. A long-estranged son, Nate Phelps, said his father had been voted out of the congregation in the summer of 2013 "after some sort of falling out," but the church refused to discuss the matter. Westboro's spokesman would only obliquely acknowledge this month that Phelps had been moved into a care facility because of health problems.
Fred Waldron Phelps was born in Meridian, Miss., on Nov. 13, 1929. He was raised a Methodist and once said he was "happy as a duck" growing up. He was an Eagle Scout, ran track and graduated from high school at age 16.
Selected to attend the U.S. Military Academy, Phelps never made it to West Point. He once said he went to a Methodist revival meeting and felt the calling to preach. Ordained a Baptist minister in 1947, he met his wife after he delivered a sermon in Arizona, and they were married in 1952.
Phelps was a missionary and pastor in the western United States and Canada before settling in Topeka in 1955 and founding his church. He earned his law degree from Washburn University in Topeka in 1964, focused on civil rights issues.
But in 1979, the Kansas Supreme Court stripped him of his license to practice in state courts, concluding he'd made false statements in court documents and "showed little regard" for professional ethics. He called the court corrupt and insisted he saw its action as a badge of honor. He later agreed to stop practicing in federal court, too.