Jon Brower Minnoch
Here is a Guinness World Record link to Jon Brower Minnoch, weighing at 635 kilograms.
"In order to get to University Hospital, Seattle, it took a dozen firemen and an improvized stretcher to move him from his home to a ferry-boat. When he arrived at the hospital, saturated with fluid and suffering from heart and respiratory failure, he was put in two beds lashed together. It took 13 people just to roll him over."