Mr. Mitchell, known as Bob, was born in Bridgeport, Conn. He attended the Wooster School (by winning a scholarship for paperboys) and Vassar College, where he was part of the second coeducational class in the school’s history. At Vassar he was a popular and charismatic student — and was also known for outrageous stunts. At one point, in order to attend more classes, he began impersonating one “Kaj Mimchel,” a Czech exchange student. The Vassar faculty was deeply impressed by this bright and charming foreigner; only months later did they discover that Vassar had no exchange program with Czechoslovakia.
Mr. Mitchell then attended Fordham Law School where he received a J.D. in 1981.
In 1986 he married Cornelia S. Guest, daughter of the late John and Margaret Guest of Fishers Island and New Canaan, Conn. They had triplets, and spent many happy summers on Fishers Island. They were divorced in the mid-2000s.
He loved traveling to France and Ireland, and was also a formidable backgammon player. He was best known to his friends and family for his humor, big heart, and larger-than-life personality.
Mr. Mitchell was devoted to his three children and large extended family. He is survived by his children, Andrew, Aune, and John (“Jack”) Mitchell, a brother, Ivar Mitchell of Vero Beach, Fla., and a sister, Louise Lipnick of Seattle.
A funeral service for Mr. Mitchell will be held on Monday, July 24 at 12:30 PM at Riverside Memorial Chapel, 180 W. 76th Street in New York. In lieu of flowers, donations may be made to the Bone Marrow Foundation, 515 Madison Avenue, Suite 1130, New York, N.Y. 10022, http://bonemarrow.org.