Cargill MacMillan Jr ., billionaire heir to the Cargill Inc . business empire, has died in Southern California at age 84 of Parkinson’s Disease. MacMillan’s death occured at his home in Indian Wells, where he lived for the last 21 years. Cargill MacMillan Jr. was worth billions based on his share of his family’s company, Cargill Inc., the largest private corporation on earth. MacMillan was the great-grandson of W.W. Cargill , the son of a Scottish sea captain, who founded Cargill Inc. as the American Civil War ended. Cargill MacMillan Jr. was a Cargill Inc. board member for 31 years.