Warren Frost, the actor who played Doc Hayward in the seminal 1990s TV series Twin Peaks, has died. He was 91. Frost was perhaps best known for his role on David Lynch’s groundbreaking ABC series, a role he reprised for the upcoming Showtime reboot. He also memorably played the father of George Costanza’s fiancée Susan, “Mr. Ross,” in Seinfeld; was a regular on the soap opera As the World Turns; and guested on several 1990s sitcoms. Frost reportedly succumbed to a long illness at his home in Virginia. He was surrounded by friends and family, including his son, Mark, who co-created Twin Peaks with David Lynch and is involved with the Showtime reboot. In a statement of tribute Mark released today, he indicated that his father was also a World War II Navy veteran who stormed the beaches of Normandy on D-Day. “We’re grateful to have shared him with the world for as long as we did,” he wrote.