His family said he had multiple health issues, including pneumonia.
"It is hard to imagine anyone who will by the level of their skill and personality have a greater influence on the sport he loved so much," USA Volleyball Chief Executive Doug Beal said in a statement. "Gene's accomplishments are legendary, and he was truly someone who became larger than life."
Selznick was born in March 19, 1930, in Los Angeles, where he lived for most of his life outside of a stay in Brooklyn during his youth.
He attended Manual Arts High School in Los Angeles, where he played volleyball. He later played the sport when he was stationed in Okinawa with the Army during the Korean War.
His broad-shouldered, barrel-chested, 6-foot, 2-inch frame could usually be found on a beach, especially in Santa Monica, where he showcased his talents and organized some of the first sand tournaments.
"There are still [Will Rogers] State Beach hangers-on who are convinced that the recent oil seepage off Santa Barbara resulted from reverberations from Selznick cannon shots pounded into the sand," The Times' Patrick McNulty wrote in a 1969 article about the sport.
Selznick was a dominant player who won 38 of the 63 tournaments he played in, with 19 runner-up finishes. He excelled on offense and defense, on the sand and on indoor courts.
He was captain of the U.S. men's national volleyball team from 1953 to 1967, and his teams won world championships in 1960 and 1966.
The versatile Selznick also coached the men's Olympic beach volleyball team of Sinjin Smith and Carl Henkel to a fifth-place finish in Atlanta in 1996 and the women's Olympic team of Misty May-Treanor and Holly McPeak to fifth place in Sydney in 2000.
"The first time I met him, to be honest, he really rubbed me the wrong way," McPeak said. "He told me how bad I was and that I could really use some work.
"But as soon as I let him into my life, he was a great confidant and a great friend and really helped me."
Selznick, who was inducted into the Volleyball Hall of Fame in 1988, had endeavors outside of the sport. He owned parking lots along the Sunset Strip and managed restaurants. He loved to dance and had a famous sweet tooth that would rival that of any child. But he never strayed far from the game, one in which he earned countless honors and awards.
"I think he's probably put more effort and time into this sport than any other individual in the history of it," said his son, Dane, who also coached in the 1996 and 2000 Summer Olympic Games.
Selznick is survived by his sons Dane, Bob and Jack; and a grandson, Shane.